Nigeria's military leader told America's U.N. Ambassador Andrew Young today that the Anglo-American proposals for a peaceful transition to independence in war-torn Rhodesia "are dead," a position that ends pivotal Nigerian support for the proposals

Lt. Gen. Olusegun Obasanjo also told Young that he felt the initiative in bringing a solution to the war in Rhodesia has gone to the Soviet Union, Young said. The comment came a day after the British announced a new Anglo-American effort to hold an all-parties conference.

Obasanjo "is inclined to say that the Anglo-American proposal is dead while I prefer to say it's sleeping," Young said. "He sort of feels the initiative has gone to the Soviets, who have a good relationship" with the Patriotic Front, Young said.

Nigeria is an influential force on the African continent, representing one of every four black Africans. It has played a crucial role in seeking a solution to the Rhodesian war and convincing other African leaders to support the proposals. Obasanjo's statement to Young, who arrived here last night after talks with President Sekou Tource in Guinea, seemingly put the British and American plan to resolve the Rhodesian conflict in grave jeopardy.

Patriotic Front guerrillas, under co-leaders Joshua Nkomo and Robert Mugabe, are escalating an insurgent war against the white-dominated bi-racial Rhodesian government of Prime Minister Ian Smith. The Rhodesian government recently retaliated against the guerrillas with widespread bombing raids on their bases in the neighboring black-ruled countries of Zambia and Mozambique.

A Nigerian government press release issued after Young's comments quoted Obasanjo as telling Young the Anglo-American proposals were dead after receipt of a special message from President Carter that the U.N. ambassador delivered.

Young did not mention Carter's message to the Nigerian leader in an earlier interview and was unavailable for comment later.

The press release said Obasanjo "called on the liberation army of the Patriotic Front to close ranks and double its efforts to complete the liberation of Zambabwe," the African nationalist name for Rhodesia.

Obasanjo had decided earlier to give the Anglo-American plan a trial because of previous American assurances that it would work, the press release continued, but "those who initiated the proposal must admit failure since the proposal has failed to take off 14 months after it was put forward."

Until September, Nigeria was intricately involved in British and American efforts to get the Patriotic Front leaders to an all-party peace conference with Rhodesian government leaders. British and American negotia- indicated they would get the Smith government to attend, but Smith initially refused.

During his visit to the United States, Smith agreed to attend such a conference without preconditions. At the same time, his troops were attacking Patriotic Front bases in Zambia and Mozambique. Both guerrilla leaders Nkomo and Mugabe, in reaction to the raids, said they would no longer consider a conference with Smith.

Mugabe also said he no longer wanted the American government involved in the effort to bring majority rule to Rhodesia.

Young said Obasanjo "is inclined to think that armed struggle has to go on but he is not opposed to talks."

In the course of 2 1/2-hour talks at Obasanjo's barracks headquarters, Young said, the Nigerian leader also raised the question of American resolve over the future of U.N.-supervised elections in Namibia.

Under a U.N. resolution, South Africa was to hold elections supervised by the world body by the end of this year. The original resolution, strongly backed by the United States, Britain, Canada, West Germany and France, apparently has been rejected by South Africa. This raises the possibility of U.N. economic sanctions against the white-ruled country.

Young said he assured the Nigerian leader that the U.S. government was still committed to the U.N.-supervised elections in Namibia leading to independence. The Nigerian press release said Young assured Obasanjo that the United States would not recognize the South African-backed elections there scheduled for next month.

Obasanjo's concerns were laid out to Young before the two meet today. The semiofficial Daily Times, in an editorial titled "Letter to Andy Young," had recalled the ambassador's last visit to Nigeria in March, with President Carter. At that time, the editorial said, Nigeria began "a honeymoon with America."

But "America has not been able to deliver on its promises, [on Rhodesia, Namibia and South Africa] and we ourselves are beginning to have some difficulty believing in your country's sincerity, let alone its will."

Young said he thought it was a "good" editorial.

[Young was to have visited Zambia on Saturday as part of a swing through the "front-line" states on the Rhodesia issue, but his office at the United Nations said those visits were postponed until after the newly announced trip to the area next week by Briton Cledwyn Hughes.]