A dispute over Tanzania's military overthrow of Ugandan dictator Idi Amin tonight disrupted the carefully cultivated image of black African solidarity at the opening session of the Organization of African Unity summit.

The dispute brought into the open one of the most divisive issues facing the leaders of black Africa - how they should react to human rights violations in neighboring states on the continent.

While black Africa has been quick to condemn human rights violations by the white governments of South Africa and Rodesia, only Tanzanian President Julius Nyerere criticized Amin's government for the brutal treatment of its own people. It was Nyerere's army that finally overthrew Amin.

Many African leaders fear that Tanzania's actions may have set a precedent, and Sudanese President Jaafar Nimeri accused Nyerere tonight of violating the OAU Charter by resorting "to the sword" to overthrow Amin.

According to the Sudanese leader, Nyerere exhibited "limited national vision" by invading Uganda.

Nimeri's attack stood in sharp contrast to the opening speech by host President William Tolbert of Liberia, who clearly referred to Amin's government in Uganda when he criticized the unwillingness of his fellow African leaders to speak out against human rights violations on the continent.

In a keynote speech repeatedly interrupted by applause, Tolbert told the crowded opening session of the conference that the OAU's heretofore inviolate principle of noninterference "has become an excuse" for African leaders to remain silent on clear instances of human rights violations.

"Today we witness repeated aggression between sister states," he said, "leaving the principle of noninterference without substance."

He cited the 4 million refugees in Africa "resulting from brotherly estrangements" between OAU members.

Tolbert, the incoming chairman of the OAU, recommended that the organization's 16-year-old charter be amended to protect fundamental human rights; make provision for a pan-African peacekeeping force that "can promptly respond" to various contingencies, be specific on regional economic cooperation, and formulate a "cohesive policy on refugees."

Tolbert also said he supports the claims of the Palestinians in Israel, an issue connected here to the Egyptian-Israeli peace treaty. But he stopped short of meeting Arab demands to criticized the treaty.

Two proposed resolutions - one condemning the treaty and the other calling the treaty a step toward progress - are scheduled to come before the summit.

Egyptian President Anwar Sadat, with several security men standing close by, sat impassively during Tolbert's speech.

Other Arab delegations here have piintedly ignored the Egyptian president. Nevertheless, a threat by North African Arab delegations to try to have Egypt expelled from the OAU did not materialize.

"Africa cannot accept the presence of Israel on Arab land," Tolbert said. "We must insist on the legitimate rights of the Palestinians to their home."

Turning to Africa's development since independence from colonial rule, Tolbert said, "The sovereignty we win is empty" if it produces "poverty and brutality."

Africa is suffering from stagnating, if not declining, rates of economic growth, Tolbert said, calling for "a new African economic order."

In an emotional appeal, guerrilla leader Joshua Nkomo asked the 37 national leaders and high-level delegations from 11 other African states to provide more military hardware to support insurgent armies fighting in Zimbabwe-Rodesia, Namivia (South west Africa) and South Africa.

Nkomo was harsh in his criticism of the government of Abel Muzorewa in Zimbabwe-Rhodesia and of the West's role in supporting the white-minority regimes of southern Africa.

"The people of Zimbabwe, Nimivia and South Africa are being massacred by the people who are supported by the West," said Nkomo, who receives considerable support from the Soviet Union.

Referring to the newly elected government in Zimbabwe-Rhodesia, Nkomo said, "The British, by their maneuvers, have substituted [former Rhodesian prime minister Ian] Smith and put in Abel Muzorewa. They have put in a black face so the situation can become confused."