Ugandan President Idi Amin admitted yesterday that there has been a mutiny in his army last weekend and a gun battle at military police headquarters in Kampala last night.

In neighboring Tanzania, refugees continued to pour out of Ugansa and claim that Amin has launched a nationwide massacre of two predominantly Christian tribes, the Langi and the Acholi. They said Amin believes the tribes were at the heart of the coup attempt.

Amin made the admissions of mutiny and a gun battle in the Ugansa capital as the diplomatic repercussions of the recent violent developments in his country mounted in world capitals.

In Washington, President Carter said that recent actions in Uganda had disgusted the entire civilized world. He was commenting on the deaths last week of Ugandan Aglican Archbishop Janani Luhum and two Cabinet ministers, together with other reports of killings in the African country.

In London, politicians of all parties pressed the British government to make clear that President Amin would be unwelcome if he came to Britain for the Commonwealth summit conference and Queen Elizabeth's jubilee celebrations in June.

But Amin insisted yesterday that he planned to lead a delegation of 250 people, including dancers, to London for the June events.

The U.S. Department, voicing deep concern over what it called massive violations of human rights in Uganda, endorsed Britain's call for a probe of the situation by the United Nations Human Rights Commission, now meeting in Geneva.

In his latest statements above violence in Uganda, Amin said "dissident troops" mutinied last Saturday at Mubende, 100 miles west of Kampala, but that order was restored after about six soldiers were killed.

Amin claimed that the alleged plot was to have climaxed with an airborne landing of paratroopers from the United States, Britain or Israel. He said the paratroopers were to fly in from an aircraft carrier of undisclosed nationality and capture several towns in Ugansa. He did not elaborate and it was unclear whether he believed that any of the three nations was directly involved in the coup attempt.

A spokesman for the U.S. State Department called the allegation "absurd" and an Israeli Foreign Ministry official said, "I know nothing about it." No comment was immediately available from the British government.

The Ugandan president said that last night at military police headquarters in Kampala a group of soldiers from the Langi and Acholi tribes "decided to shoot other tribes" and one man was killed in the ensuing violence.

Amin denied that there was a purge of the two tribes, which formed the power base of former President Milton Obote.

Amin's personal admission that there had been an uprising and ssome killings was regarded as a serious development since he was generally denied such killings during his six years in power, in which it is estimated that anywhere from 30,000 to 300,000 persons have been killed.

It is also impossible that Amin, who has been known to make wild charges in the past, came up with the claim of foreign involvement in the alleged rebellion by the troops as a maneuver to divert attention from the burgeoning reports of the massacres.

He also denied Tanzanian newspaper report that he personally shot Archbishop Luwum.

Refugees from Ugansa said in Dares Salaam today tht a large-scale massacre of the Langi and Acholi tribes was now going on.

In Sydney, the archbishop of Canterbury, accused by Amin of being involved in plotting against Uganda, said he wanted to see an end to Amin's rule. "I'm astonished that he's got away with it for as long," said Donald Coggan, primate of the Church of England, who was a personal friend of Luwum.

In New York, a group of black American civil-rights leaders condemned Amin's government for what they termed its total contempt for human life.

At the United Nations, Secretary General Kurt Waldheim sought clarification of an apparent offer by Amin to permit any African government to investigate the recent events in Uganda, about which Waldheim again expressed concern.

The All-African Conference of Churches released a document in which Archbishop Luwum pleaded with Amin for a chance to show the world that "I am innocent" of charges that he was involved in a plot against the president. Luwum reportedly was taking the paper to Amin on the night he was killed.

In the document Luvum called himself Amin's "servant un the Lord's vineyard' and said, "Since I am still present, it is only fair to the international world, the public of Uganda and myself that I be allowed to speak.

"For the sake of myself and the church I lead, I would like more concrete evidence about these serious and far-reaching allegations," Luvum's appeal said.