After six months and 10 deaths by willfull starvation, the hunger strike by Irish Nationalist prisoners in British-ruled Northern Ireland has lost momentum because of the increasing intervention by relatives requesting that hunger strikers on the brink of death be given emergency medical treatment to save their lives.

But the Provisional Irish Republican Army has insisted that the hunger strike will continue, while British officials appear less likely than ever to grant or agree to a compromise of the prisoners' demands until the protest ends.

It remains a macabre test of wills between the Provisional IRA and the British government of Prime Minister Margaret Thatcher. With each death of a fasting Irish Nationalist terrorist in the Maze Prison outside Belfast, it has become more difficult for either side to back down from what each regards as the most important battle yet in a decade-long war.

Even before two more hunger strikers were removed from the fasts by relatives this past weekend, a government spokesman here insisted that "the IRA are on a loser and they know it." In a somber office in Stormont Castle, a replica of a medieval stronghold that houses the British officials who run Northern Ireland, he said, "Support for the hunger strike is dwindling. Relatives of the prisoners are pressuring the IRA to end the protest."

Four hunger strikers have now been removed from the protest by relatives in the past five weeks. When each lost consciousness, transferring legal responsibility for their lives to their next of kin, parents or spouses authorized emergency treatment to save their lives.

In the most recent case, the parents of 24-year-old provisional IRA member Lawrence McKeown intervened on Sunday when he lost consciousness after refusing food for 70 days. On Friday the parents of Matt Devlin, who had been fasting for 52 days, did the same thing. So far, each of the prisoners removed from the fast by relatives and treated in a hospital outside the prison has resumed eating voluntarily.

Five prisoners are still on hunger strike, the longest for just over a month. Sources close to the Provisional IRA said every hunger striker who is removed from the protest or dies will continue to be replaced from a group of 50 to 60 volunteers among 400 Provisional IRA members in the Maze.

But a splinter Irish national paramilitary group, the Irish National Liberation Army, announced over the weekend that it will no longer add one of its members to the hunger strike for every three contributed by the Provisional IRA because, with just 28 INLA prisoners remaining, "All of our prisoners will be dead within six months." A statement attributed to the INLA prisoners said, "It is obvious now that the British government are being far more intransigent than we first expected."

With the hunger strike's militant Irish nationalist supporters venting their frustration in arguments about the campaign's tactics at a weekend conference in the Northern Ireland town of Dundalk, there now appears to be at least a month before another faster would be near death.

Informed sources in Belfast said the Provisional IRA faces several difficult options during the interim: finding a way for the hunger strikers to emphasize more forcefully to their relatives that they do not want them to intervene; persuading a prisoner to go back on the hunger strike and reverse the trend of family intervention; continuing the hunger strike with a possible further loss of momentum if more prisoners are removed by relatives; or deciding to end the protest after announcing that it has already accomplished many of the movement's objectives.

"I think there are signs that the Provisional IRA and their supporters have recognized the British government is not to be blackmailed by this type of activity," said Britain's Northern Ireland secretary, Humphrey Atkins, before the weekend developments.

"I think they realize opinion in the world, which they have been trying to swing and stir up, is gradually realizing the precise nature of what they are doing, which is to carry on inside the prison the struggle in which they have been engaging for 10 years outside," Atkins said.

"Faced with the failure of their discredited cause, the men of violence have chosen in recent months to play what may be their last card," Thatcher, who has personally supervised the government's handling of the hunger strike, said in her last major public statement on the subject during a visit to Belfast earlier this year. She said her government "is not prepared to legitimize their cause by word or deed."

Yet the IRA and its supporters contend they have gained from both the hunger strike and a recent accompanying surge of attacks against the security forces and property in Northern Ireland.

"If anyone ever had doubts about our ability to maintain the military struggle, they should be gone now," said a spokesman for Provisional Sinn Fein, the political arm of the outlawed Provisional IRA, at its headquarters in a small building surrounded by the debris of rioting in the heart of the Catholic Irish nationalist ghetto in West Belfast.

The "Provos," as the Provisionals are called, appear to have greatly increased their base of support among Irish nationalists in Northern Ireland and the Republic of Ireland during the hunger strike. Maze prisoners won surprisingly large numbers of votes in the recent Irish national election, with hunger striker Kieran Doherty, who has since died, gaining a seat in the Irish parliament.

The first hunger striker to die, Bobby Sands, won a seat in the British Parliament from a Northern Ireland constituency on the Irish border. Recently elected to replace him was a leading Provisional Sinn Fein member, Owen Carron, who publicly defended the Provisional IRA's campaign of violence to try to push Britain out of Northern Ireland.

"A new nationalist movement can emerge from the whole prison protest," Daithi O'Connail, a Provisional Sinn Fein vice president, said in Dublin after the June Irish national election. He compared the present situation with the rise of nationalism in Ireland after 1917 when the British executed the leaders of the 1916 Easter Rising in Dublin.

This specter haunts the Irish government and moderate Catholic Irish nationalist leaders in Northern Ireland. They seek gradual, peaceful unification of Ulster with Ireland through negotiation with Britain. They fear the increase in tension and apparent support for the Provos during the hunger strike could destabilize all of Ireland, with bloody consequences.

The sooner the hunger strike can be resolved, "and the sooner the IRA gains can be wiped out, the better," Irish Prime Minister Garret FitzGerald said recently after repeated private and public entreaties to the British government and the prisoners to reach a settlement.

"I appreciate the IRA are a threat to our government, to our democracy, and not a threat to Britain," FitzGerald said. "It's we who have to live with them. It is we who have to fight them and save democracy here."

The Thatcher government "may well defeat the prisoners" who are on hunger strike, said John Hume, leader of the Social Democratic and Labor Party, which represents the majority of moderate Catholics in Northern Ireland.

"But it would be a pyrrhic victory because the underlying problem has been made far worse. The terrorists have more recruits and they have more money from Irish Americans. The community in Northern Ireland is more polarized and there has been serious political dislocation."

In Britain, the hunger strike has hastened another agonizing reappraisal of Britain's role in Northern Ireland. The opposition Labor Party is considering breaking the tradition of bipartisan British policy on Ulster by declaring as its long-term goal the eventual unification of Ireland.

This conflicts with the ruling Conservative Party's deeply rooted support for the union between Northern Ireland and the rest of Britain, although a growing number of Conservative politicians believe the time may have come for that to be changed.

"We will have to have more debate on Northern Ireland now," said one influential Conservative back-bencher in Parliament. "Most British politicians would give it to Ireland immediately if it weren't for the fear of bloodshed."

"I fear we must conclude that Northern Ireland is in almost total stalemate, both politically and militarily, with alarming adverse social and economic circumstances," Parliament was told recently by former Labor prime minister James Callaghan. He advocates making Ulster a "broadly independent" state, with some ties to both Britain and Ireland, in which the Protestant majority and Catholic minority would have come to terms with each other.

It was wrong, Callaghan argued, for successive British governments, including his own, to work primarily to defeat the IRA without resolving the larger conflict from which terrorism springs.

"History shows that during the past 25 years there have been only six years without political disruption or violence of one kind or another," he said. "Those periods occur when, temporarily, the IRA has shot its bolt and falls back exhausted. However, when it has regathered strength, the battle starts again."

Although Callaghan's suggestion has been criticized as the recipe for a civil war in the province, much of what has been said and written in a growing national debate in Britain about the future of Northern Ireland agrees with his basic conclusion that present British policy is unworkable.

But Atkins, in an interview, reiterated the Thatcher government's commitment to combatting Irish nationalist terrorism as its top priority. "You have a group of people whose declared objective is to take over the government of both Northern Ireland and Ireland," he said.

"They first seek to destroy the government of Northern Ireland, and then the government of Ireland, and then set up a socialist dictatorship. They are trying to do it by force because they know they cannot do it by democratic means. They've been trying to do it by force for 10 to 12 years now, and they are failing."

This is the context for the hunger strike and the Thatcher government's response to it. Hunger strikes have been an Irish form of protest for more than a thousand years and a weapon of Irish nationalism throughout this century, often in protest against the Republic of Ireland's proscription of the IRA and refusal to back its armed struggle against Britain in Northern Ireland.

The issues leading to this hunger strike began to intensify in 1976, when British officials decided to abolish special treatment for nationalist prisoners and instead initiated a policy of "criminalization." Suspects convicted by judges sitting without juries, because of past intimidation of jurors, were imprisoned as ordinary criminals in the H-shaped cellblocks of a new prison, the Maze.

Shortly after the criminalization policy began, newly convicted Irish nationalist terrorists protested being treated as ordinary criminals by refusing to do prison work or wear prison clothes, wrapping themselves instead in blankets that became symbols of their defiance.

Hundreds of Irish nationalist prisoners joined the protest over the past five years. In 1978, they began refusing to wash or slop out their cells, instead smearing their excrement on the walls. Then they first made the five demands now at the center of the hunger strike: no prison clothes, no prison work, free association with other nationalist prisoners, expanded mail and visitor privileges, and restoration of lost time for good behavior.

This "dirty protest" attracted international attention to the prisoners, who, as the European Human Rights Commission pointed out in ruling they were not entitled to political prisoner status, had themselves created the filthy conditions in their cells, which were periodically cleaned only to be fouled again by the inmates. After an abortive hunger strike by some of the protesting prisoners last year, the dirty protest was ended and replaced in March by the hunger strike.

During the years of protests by Irish nationalist prisoners, British officials have made a number of reforms for conforming prisoners, including expansion of mail and visitor privileges and allowing inmates to wear their own clothes during leisure hours and prison-issued civilian clothes while working.

British officials have indicated that more changes would be considered if the hunger strike ended. These included allowing prisoners to wear their own clothes all the time, giving them more opportunities for vocational training and other education, and allowing more association in free time among prisoners in larger numbers. But officials insist that all prisoners must still participate in some form of industrial prison work and cannot manage their own time.

British officials also refuse to negotiate any of this with the prisoners or promise any future changes in the prison regimen so long as the hunger strike lasts.

Much of the struggle now is for public opinion, particularly in the United States, where financial and political support from Irish Americans is seen by both the IRA and the British government as crucial to their cause.

The government has sent senior British officials on tours of the United States to brief politicians and journalists, has allowed American journalists inside the Maze, and has issued what it calls "fact files" on the hunger strikers and other Irish nationalist prisoners .

They point out that of the more than 400 protesting prisoners -- nearly 100 of whom have volunteered for the hunger strike -- 74 have been convicted of murder, 45 for attempted murder, 118 for explosive offenses and 92 for illegal gun possession in attacks on both security forces, civilians and businesses in Northern Ireland.

The Provos, operating from their small headquarters in Belfast and Dublin but seemingly flush with cash, ape the government's tactics in the propaganda war. They have their own polished spokesmen, issue Provo press cards, and telex news releases around the world. They have sent on U.S. publicity and fund-raising tours both their own representatives and a number of hunger strikers' relatives. They have publicized statements from the prisoners smuggled out of the Maze.

While backing away from previous demands to be treated differently than other prisoners in Northern Ireland, the hunger strikers have continued to hope to pressure the government into creating conditions in the Maze that would make it more like a prison camp, including allowing the prisoners to substitute houskeeping chores and Irish nationalist cultural education for industrial prison work and to communicate with the authorities through their own commander in prison.

The Thatcher government has refused to agree. Despite several promising mediation attempts, British officials have disputed contentions by Irish government and Ulster Irish Catholic leaders that a compromise could easily be reached on the prisoners' demands.

"They think we can do this or that and the problem will go away," said a senior British official. "We think it won't. The Provos will just want more slices of the salami. Our concern is that every time someone comes up with a new idea for compromise it encourages the Provos to think here is someone putting pressure on the British government and it will eventually give way. If we give in this, they will think they can push a bit harder and we will give a bit more."

The Thatcher government first expected the prisoners to give up the protest once they realized they would be left to die rather than achieve all their demands. The government then expected that, if its security forces could largely confine violent reactions to hunger strike deaths to Catholic Irish nationalist areas in the province, Irish Catholic community pressure would build to stop the protest. Instead, sympathy for the prisoners and antagonism toward the British government have greatly increased.

Hume said that Thatcher "has a total lack of feel for the Irish problem. I can't explain to her how the Irish Catholic community feels about the hunger strike without necessarily supporting the IRA.

"Try to get yourself into the prisoners' psychology," Hume said. "They went through the dirty protest for all those years, their leader Bobby Sands died and was glorified, and now many more have died. In this group psychology, it is more difficult to live than to die. They are not living in the same world as you or I."

Irish nationalist prisoners in the Maze, who normally refuse to talk to their guards, communicate among themselves in Irish shouted down corridors or pass messages by various time-honored inmate methods.

Prisoners on hunger strike are eventually moved to beds in private rooms in the prison hospital, where they can read newspapers, listen to radio, watch television and talk to other hunger strikers in the evenings. They ignore meals left in their rooms all day, every day and take only spring water. When each hunger striker nears death, his relatives are allowed to move into nearby rooms and stay with the dying young man.

"Basically, the relatives are in an emotional state," said one source who has spoken to a number of anxious parents and wives of hunger strikers who will not discuss their feelings with reporters. "They are desperate for anybody to do anything to help them. But they are afraid of anything that would make them put pressure on the prisoners. That's why there was never much to the so-called revolt of the relatives."

But over the weekend, after relatives took two more prisoners off the hunger strike, this same source said, without being able to talk further with any of the relatives, "I think it's breaking up. The psychological pressure of solidarity is being broken. The men still on hunger strike will be asking themselves, 'What are we dying for?' "

The increasing frequency of explanatory statements from the protesting prisoners and their supporters shows that the relatives' anxiety and public pressure from the Irish government on the Provisional IRA has had some impact. On the other side, the British government remains under pressure from the Irish government and a growing number of British politicans and media voices to extricate itself from the crisis and consider ways to resolve the question of British rule of Northern Ireland.

But Thatcher's government appears reluctant to do anything that would arouse the strong, perhaps violent opposition, of Ulster Protestants and their still numerous sympathizers in the rest of Britain.

"Yes, I think it is true that people are becoming concerned about the cost and loss of lives in Northern Ireland," Atkins said when asked about the ongoing debate in Britain about Ulster. "Times are difficult and the cost is high. But, at the same time, I think people understand the reasons for it.

"As awful as this sounds," said another government minister, "I don't think people have seen enough deaths of British soldiers in Northern Ireland. It's not yet anything like Vietnam for the United States."

Thatcher also must avoid a right-wing revolt in her party over Northern Ireland at a time when she is under fire from its left wing for her economic and social policies. She stands staunchly behind the legal guarantee Britain gave Ulster Protestants when the Irish Free State, now the Republic of Ireland, broke away from Britain in the 1920s: the six counties of Ulster would remain part of Britain so long as the majority of its people wanted it that way.

But advocates of change in Northern Ireland, including British politicians reluctant to put their views on the record, are annoyed that the Ulster Protestant majority uses this guarantee to block any proposed change it dislikes or fears.

Irish Prime Minister FitzGerald has said that many British politicians, in private discussions with him, "freely recognize that the ultimate solution that would be desirable would be one that would bring north and south of Ireland together so that Britain could disengage."

But the Irish government itself is "fearful of precipitate unification," in the words of one senior official. "We worry about the economic and violence problems," he said, which could result from a rapid British withdrawal.

Instead, FitzGerald and the Catholic Social Democratic and Labor party in the north favor a gradual approach in which Ulster Protestants might be persuaded to consent to a federal Ireland. Under this plan, Ulster would have its own regional government and control of legislation on matters like education, marriage, divorce and contraception, on which Ulster Protestant views differ sharply from Irish Catholics.

Some new ties between a united Ireland and Britain also could be forged, in this view, with Ulster residents retaining British citizenship. Many Irish citizens now live in Britain while retaining Irish citizenship.

Irish officials and moderate Catholic Irish nationalist leaders in Northern Ireland see the talks begun last year by Britain and Ireland on improving cooperation between the two countries as a possible first step down the road to a new relationship for both countries, including Northern Ireland.

While British officials are more cautious about this aspect of what so far have been only preliminary talks on economic cooperation and cross-border citizenship questions, one senior official in London said the British-Irish dialogue represents "a recognition by both governments that we've got to reverse this process of walking away from each other."

All suggestions for change offered in the debate over the future of Northern Ireland "still fail to come to grips with the basic problem," said a Western diplomat who has watched Northern Ireland closely, "which is to try to get the Protestant majority to relax and accept change. Everything has been having only the opposite effect."

"They have to get the Protestants to learn to walk and it has to be a gradual process. There are times when they seem more willing to move. Today is one time when they seem most firmly sat down."