The Anglo-American peace initiative over Rhodesia appears perilously close to failing as white and black leaders of the 3 month-old transitional government continue to hold out against an all-parties conference and militant nationalist guerrillas stiffen their conditions for ending their war.

The refusal in particular of the three African members of the government's executive council to go to a Western-sponsored conference comes at a time of a full-brown public crisis of confidence among both its black and white supporters over its record to date and ability to survive.

Since the interim government was set up under an agreement signed here March 3, its rule has been marked by repeated crises within the executive council, threats by its leading black member, Bishop Abel Muzorewa, to withdraw, and several accidental massacres of African civilians caught in crossfires between guerrillas and government troops.

At the same time, there has been no significant progress toward a ceasefire despite a formal appeal to the guerrillas to lay down their arms over a month ago. Without one, it is seriously doubted whether elections for black majority government can be held before the end of this year as provided for under the March agreement.

All this explains why there is mounting grassroots pressure now from the African population for the transitional government to attend an all-party conference. But its black leaders apparently fear this step will spell political disaster for the March agreement and themselves.

On the diplomatic front, reports circulating here say the United States and Britain have almost given up on their orginal idea of convening a general peace conference. They are now said to be simply trying to get the internal and external black nationalist leaders to talk directly to each other about some kind of a political settlement to end the escalating war.

But one of the nationalist guerrilla leaders, Robert Mugabe, has rejected outright such direct talks while the other, Joshua Nkomo, is hinting strongly the only issue left for them to discuss with the transitional government is surrender terms. The two men lead separate factions of the guerrilla alliance, the Patriotic Front, which operates from Zambia and Mozambique.

Thursday, Mugabe told British envoy John Graham and American Ambassador Stephen Low that he was only willing to attend an all-parties conference called to to discuss a new constitution for black majority rule in Rhodesia. The two Western envoys met with him in the Mozambican capital of Maputo.

They have been visiting Salisbury and various other frontline African capitals for the past two weeks in another Western bid to get talks under way involving all the parties.

Meanwhile, Nkomo said in an interview here Saturday with the black newspaper, the National Observer, that there would be no end to the fighting until there was "a clear transfer of real power" to the Patriotic Front. He added:

"You know how wars have ended. They have ended with very short negotiations. But first it must be confirmed there is a real transfer of power."

His remarks reflect the Front's attitude that Rhodesia is in a "war situation" where one side eventually has to surrender to the other and the winner takes power.

The hardening position of the Patriotic Front appears to reflect its awareness both of the guerriallas' growing strength inside Rhodesia and the slow crumbling of support for the transitional government.

The military and civilian death toll in the war has reached roughly an average of 100 a week now and there is now sign ofa letup in hte fighting. The Front claims that 97 percent of the country is now "operational territory" for its guerrillas.

Meanwhile, there a sign everywhere of a growing disillusionment with the interim government and an increasing number of calls from the African public in particular for it to agree to an all-party conference.

Rhodesian Prime Minister Ian Smith himself expressed disappointment with the failure so far of the government to arrange a cease-fire as well as its general record. In an interview with the British Broadcasting Company earlier this week, he remarked that "We are not succeeding as well as we had hoped . . . I am critical of our efforts so far (to get) a cease-fire . . . We have to improve our performance."

The latest issue of the rightist monthly, Rhodesian Viewpoint, said the interim settlement reached in March between Smith and the three moderate black leaders had shown itself to be a "recipe for disaster" and had so far failed to achieve any of its main goals.

Far more significantly, moderate black opinion is also truning against the March agreement. Both the National Observer and the main black daily in Salisbury, the Zimbabwe Times, came out with editorials Saturday attacking the transitional government and demanding that it attend an all-parties conference. The two newspapers were previously strong supporters of the new government and in particular of Bishop Muzorewa.

The Zimbabwe Times noted that the government had failed to achieve the three main goals of any settlement - an end to the fighting, international recognition and the lifting of economic sanctions imposed by the United Nation after the white illegally declared their independence from Britain in 1965.

Meanwhile, many African supporters of Bishop Muzorewa are also openly expressing their disappointment with him and his government. "Nothing has changed since March," said one restaurant worker. "But its terrible at home. The shooting and killing is getting worse," he said referring to conditions in his tribal reserve in Eastern Rhodesia.

"Muzorewa should get out of the government," he added.

A white adviser to the bishop, Arhn Palley, warned Bluntly in an interview with the Observer that "the interim government must carry out its promises or otherwise it will find other people will do so." The government's record has "proved to be a great disappointment."

Whether this clear shift in black and white public opinion will convince the executive council to accept soon the Western proposal for the holding of a general conference remains to be seen.

The British and American envoys left here at mid-week after a fruitless 10-day stay and talks with the executive council but are due back early this week for another round of discussions. Smith is said to be more open privately to meeting with the Patriotic Front than his black colleagues.

Saturday, Rev. Ndabaningi Sithole another of the executive council members, reaffirmed his strong opposition to an all-parties conference saying, "As far as we are concerned, the political problems have been resoved."

Even if and when the black leaders of the transitional government do agree to a conference, there is now serious doubt that Britain and the United States can find a mutually acceptable basis for a settlement, with the Patriotic Front gaining strength daily and the government here steadily weakning.

Many outside Western obsevnment here steadily weakning.

Many outside Western observers here are coming to feel that his crucial point has already been passed, leaving prospects for a negotiated settlement dim.