Ugandan President Idi Amin said today he had foiled an attempt on his life that was part of a plot to assassinate four other black African heads of state.

Speaking to the Organization of African Unity summit meeting here, Amin received applause and laughter as he indirectly confirmed earlier reports of an unsuccessful attempt to kill him last month.

Amin, a revolver strapped to his blue air force commander's uniform, said, "I captured some of the people who tried to assassinate me."

"I have got them," he added, and then suggested that the whole affair would be discussed privately with his 22 fellow heads of state assembled here.

Amin provided no clues about the exact timing and circumstances of the latest assassination attempt, the identity of the alleged assasins or whether they were still alive.

He said the alleged assassins earlier had tried to kill Marxist President Mathieu Kerekou of Benin and Marixist President Agostinho Neto of Angola, were responsible for the assassination of Marxist President Marien Ngouabi of the Congo and planned to kill leftist President Sekou Toure of Guinea.

A still mysterious mercenary raid against Benin took place Jan. 16. Two months later, Ngouabi was assassinated. A coup against Neto failed in late May, and Toure has been the object of a series of alleged plots since Guinea became independent.

Amin's audience of African political leaders, diplomats and top civil servants roared with laughter when the Ugandan explained last week's decision by the Uganda Defense Council - which he dominates - to award him "the Highest Order of the Conqueror of the British Empire."

He said he earned the distinction by making the British "run away" from East Africa.

In a more serious vein, Amin pledged his readiness to accept mediation to prevent the collapse of the already badly undermined East African Community. It once ran railroads, ports, telecommunications, meteorology services, customs and an airline for Kenya, Tanzania and Uganda.

Amin met with Kenyan Foreign Minister Munyua Waiyaki and told him that Tanzanian President Julius Nyerere is apparently willing to hold a meeting on the troubled community. Nyerere has refused to hold a meeting of the community's supreme authority since 1971 to mark his displeasure with Amin's coup ousting Milton Obote.

Aside from this note of compromise inside of the copper-topped $23 million council chamber here, OAU member states continued to trade accusations before spending the meeting's final 24 hours considering a crowded agenda of unsolved problems.

Illustrative of the mood were Somali charges of Ethiopian "black colonialism," "murder," and "massacres" which were in reply to Ethiopian leader Mengistu Haile Mariam's accusations that Somalia and Sudan were guilty of a "coordinated conspiracy" to dismember his country.

Ethiopio's Marxist leader asked the OAU to study charges of violations of member countries' frontiers and report back annually to the summit meeting.

Yet another black African failing was underscored by Congolese President Joachim Yhomby-Opango who regretted that "some of us entertain economic relations with the South African Nazis and fascists."

He named no names. South Africa claims it has some form of relations with 18 of the 49 OAU members, ranging from close trade links to direct investment.

What the Congolese leader did not mention was that his government recently rescinded a longstanding ban against allowing a French airline to use his capital. Brazzaville, as a stopover on its Europe-to-South Africa route.