The five African frontline leaders ended their summit here today with some indication that they may be ready to accept the new British-American plan for a peaceful settlement of the Rhodesia dispute provided it succeeds in removing Rhodesian Prime Minister Ian Smith from power and disbanding the white army there.

"We are saying that we will accept the Anglo-American proposals if they are aimed at helping us to achieve this objective which we have very clearly defined," said President Julius Nyerere of Tanzania, chairman of the frontline group.

Still, the indications were that serious differences exist between the African leaders and the British and U.S. governments over the makeup and role of a proposed international peacekeeping force to serve during an interim period leading to black-majority rule, as well as over the makeup of a new army to maintain order afterwards.

Despite these differences, neither the frontline leaders nor two black Rhodesian nationalist figures also attending the summit rushed to turn down the plan today, leaving hope for a possible compromise.

The most discouraging note for the latest British-American peace initative was struck in Rhodesia, where Smith was quoted as saying he rejected the proposals. "My answer, quite clearly, is that I will not accept them," he said.

Meanwhile, Zambian President Kenneth Kaunda said he had received military intelligence that the white Rhodesian army was planning to begin air raids against his country between Aug. 28 and Sept. 7, after suffering heavy casualities from black nationalist guerillas operating from Zambia.

Nyerere told a press conference after the summit gathering that the frontline states would accept the plan only if the proposals acheived the African objectives of removing Smith from power and dismantling the white Rhodesian army.

"Smith, the leader of racism there and his army must go," he repeatedly said, adding that "the West must help us to acheive this objective. That is what we are asking."

But he refused again and again to say whether he felt the British-American proposals, as they were spelled out to the frontline leaders here today by British Foreign Secretary David Owen and U.S. Ambassador Andrew Young, fulfilled these apparently key African objectives.

He indicated the reaction of the frontline states woudl not be made known formally until the proposals are published late next week after their presentation to Smith in the Rhodesian capital of Salisbury by the American and British diplomats.

Spokesmen for the Owen-Young delegation were just as noncommittal as Nyerere about how the more than three hours of discussions with the five frontline leaders had gone.

Hamilton Whyte, press spokesman for Secretary Owen, characterized the talks as "very down-to-earth, detailed and serious discussions" and said they would continue at an unspecified time and place. He stressed that the summit meeting here did not require

Nyerere and Whytle thus agreed that the issues of security during the an immediate acceptance or rejection by any party.

"This is a very complicated, very detailed and very critical point of the entire operation," he said conceeding that the talks had at time involved some "serious, tough talking."

"But it means," Whyte said, "that Owen and Young are in business, or are still in business, if you like, since everybody is always trying to suggest they embarked on what was in any case a mission impossible."

Whyte indicated that most of the "tough talking" concerned security arrangements during the proposed transition period from white to black rule in Rhodesia and the future of the present Rhodesian army as well as that of the nationalist guerrilla one now in the making.

transition and the makeup of the army were the two central issues in the current talks.

THe general impression of observers here was that two sides were still at serious odds on the security question.

Attending the summit meeting in addition to Nyerere and Kaunds were President Samora Machel of Mozambique, Vice President Quett Masire of Botswana and Vice Premier Jose Edwardo dos Santos of Angola.

[In Salisbury, the Rhodesian military command said Rhodesian forces near Victoria Falls came under rocket, mortar and automatic weapons attack from neighboring Zambia Friday and suffered three men wounded. United Press International reported.]