The government of Prime Minister Margaret Thatcher announced today that it will create an advisory assembly in British-ruled Northern Ireland as the first step toward what is intended to be a political solution to the conflict between the province's Protestant majority and Catholic minority.

The 50-seat assembly would be composed of Ulster members of the British and European parliaments and the largely powerless district councils in Northern Ireland. They would be selected by the British government to reflect proportionally the present voting strengths of the various, primarily sectarian political parties in Northern Ireland.

Britain's Northern Ireland secretary, Humphrey Atkins, told Parliament here today that the assembly would advise him on Britain's current direct rule of Ulster and consider ways of achieving elected, shared-power home rule in the province in the future. He indicated that he could also ask it to consider and advise him on topics arising from Britain's on going talks with the Irish Republic on improved cooperation between the two countries, including across the Irish-Ulster border.

Atkins said the government intended to create the assembly by administrative order later this year after discussing details with political leaders in Northern Ireland and submitting the final plan to Parliament for review. That will make it more difficult for the plan to be blocked by any Ulster politicans who oppose it.

The announcement received a mixed reception in Parliament, which debated and then renewed the government's emergency powers for direct rule of Northern Ireland, including detention for questioning and trial without a jury for suspected terrorists. The debate reflected a growing restiveness in Parliament, particularly in the opposition Labor Party, with Britian's rule of the province at a time of greatly increased tension there.

Labor former prime minister James Callagham called on the government to take bolder action to eventually make Northern Ireland "a broadly independent State" with legal protection for its Catholic minority and a "new relationship" with both Britian and Ireland. Several Labor members of Parliament are seeking to have the party adopt as a former policy goal the eventual unification of Ulster with Ireland in a federal arrangement protecting the rights of the Protestants, who would then be the minority.

The debate and the new political initiative by Thatcher's government came just days before the hunger strike by convicted Irish nationalist terrorists in the Maze Prison near Belfast is expected to reach another critical stage.

Joe McDonnell, 30, a member of the outlawed Provisional Irish Republican Army serving a 14-year sentence for illegal weapons possession, has refused food for 55 days and his condition is reported to be deteriorating steadily. He would be the fifth hunger striker to die this year, but the first in more than six weeks.

McDonnell joined the hunger strike as a replacement for Bobby Sands, elected briefly to the British Parliament, who was the first to die on May 5. Eight prisoners are now refusing food as additional prisoners join the hunger strike at regular intervals so that a death could now occur every week or two unless the protest is ended. The hunger strikers had been seeking special status as political prisoners.

No solution appears to be in sight despite some discernible new flexibility in the positions of both the Briish government and the hunger strikers following pleas to both sides by a commission of the Council of Irish Bishops. Atkins issued a long statement this week detailing ways in which the regime already had been liberalized for all prisoners in Northern Ireland and saying this process could continue if the hunger strike ended.

Atkins contended that the "northern Ireland prison regime is generous, and has been and will be administered flexibly by the authorities" and added that "there is scope for yet further development." But he said this would take time and "cannot proceed further while the hunger strike places the authorities under duress."

And answer purportedly smuggled out of the Maze from the protesting prisoners yesterday criticized Atkins' statement as being too vague. The prisoners reiterated previous demands but dropped language in previous statements demanding to be treated as political prisoners. Instead, the statement said they were asking for the changes to be made for all prisoners in Northern Ireland.

Because the increased polarization and upsurge of violence accompanying the hunger strike deaths has "been a serious setback" after a period of relaxed tension in Northern Ireland, Atkins told Parliament today, the advisory assembly the government proposed was neded "as a matter of urgency." He said there was "a pressing need to reengage people in Northern Ireland in politics," but it was not yet possible for an assembly to be elected directly or have legislative or executive powers.

Last year, Atkins failed to win agreement in talks with Ulster political leaders to devise a form of elected assembly in which the Protestants and Catholics would share such powers.

Power-sharing is opposed by hard-line Protestant loyalist politicians who instead want restoration of majority home rule in Northern Ireland that would keep Catholics a relatively powerless monority; hardline Protestand loyalists also oppose the British government's talks with the government of the Irish Republic to the south because they fear the discussions could evenutally lead to British abandonment of Northern Ireland.

Militant Protestant loyalist leader Ian Paisley vowed late tonight to wreck the advisory assembly if it is set up because one of its purposes would be to discuss Northern Ireland's constitutional future. "We have made it clear to Mrs. Thatcher we are not discussing anything with her until she quits the Anglo-Irish talks," said Paisley, who met privately with Thatcher and Atkins earlier this week.