Egyptian President Anwar Sadat today answered critics at the Organization of African Unity summit with an impassioned defense of the Egyptian-Israeli peace treaty.

Sadat's hour-long speech was greeted by strong support from most of the black African delegates, but by silence from northern African Arab officials. Delegations from Algeria and Libya, walked out on the speech.

Sadat was preceded by Nigerian military head of state Olusegun Obasanjo, who was the second speaker to raise the Palestinian issue at the two-day-old summit.

The Egyptian-Israeli peace treaty has generated controversy here. A resolution on the treaty, which was supposed to be presented to the summit Monday, has been tied up in a committee of African foreign ministers for two weeks.

One African minister said the committee has been paralyzed by bitter debate on a Libyan proposal to condemn the treaty and a resolution submitted by moderate African states to call the treaty "a step forward in the right direction." There is also a delegation from the Palestine Liberation Organization here lobbying the African leaders for an anti-Egypt resolution.

Sadat's speech was part of a concerted Egyptian diplomatic effort designed to head off an expected attempt by Libya and Algeria to exclude the Cairo government from active participation in the OAU. The Egyptian effort also is aimed at strengthening that country's position in other international forums such as the nonaligned movement and the United Nations.

The effort is considered particularly important since Arab League members have taken steps to expel Egypt and the Islamic conference in Morocco last May excluded Egypt.

Surrounded by 10 bodyguards, Sadat departed from his prepared speech on the treaty to respond to what he said was an allegation that Egypt had been aided by the United States in planning the October 1973 war against Israel.

He said the accusation had been brought to him by an African president who had been told of the alleged collusion by "an Arab personality."

"Over the Arab (world) there is an artificial atmosphere of nervousness and tension more than logic and reason," said Sadat, whose face sometimes reddened with emotion as he spoke. "That is the key to the whole situation."

Sadat said that he had planned the October war "carefully" and alone. It was conducted, he said, to regain Egypt's dignity and honor after the Israeli victory in the 1967 war. There was never any collusion with the United States, he added.

Sadat also said Arab delegates and Aplestinians here have accused Egypt of usurping the rights of Palestinians by speaking in their behalf at the Camp David discussions leading to the treaty.

"I told (American President Jimmy) Carter and (Israeli Prime Minister Menachem) Begin that none of the (Arab leaders) are able to speak on behalf of the Palestinians," he said. The charge that he usurped Palestinian rights "is not true," he added.

Sadat said he has repeatedly urged the Palestinians to set up a provisional government to effectively seek a redress of their grievances.

"Egypt would be ready to immediately recognize" a provisional Palestinian government, he said. "No other Arab leader has called for a provisional government, and I continue to call for one."

In his remarks preceding Sadat, Obasanjo said, "We are convinced that the core problem of the 30-year-old Middle East crisis - the Palestinian question - remains unresolved."

To provide a permanent solution, Obasanjo added, "any decision on the future arrangements for the homeless Palestinians must fully reflect" their wishes.