Egypt is demanding as a condition for continuing Palestinian autonomy talks with Israel that the sovereignty of Jerusalem remain part of the discussion despite a new Israeli law declaring the entire city Israel's eternal capital, diplomatic sources said today.

This is the thrust of a message from Egytian President Anwar Sadat handed today to Prime Minister Menachem Begin of Israel and to the United States. It follows an order yesterday by Sadat to delay a new round of talks that had been scheduled to begin in Alexandria this week, the source said.

The talks are unlikely to continue until Sadat receives what he considers adequate guarantees from Israel and the United States on the controversial Jerusalem law, a process that could take days or even weeks as messages pass between Cairo, Jerusalem and Washington, the source indicated.

Begin and his aides were studying the 12-page note tonight, and there was no immediate reaction from the government. But the prime minister called a special session of the Cabinet for Monday to discuss Israel's response, Washington Post correspondent William Claiborne reported from Jerusalem.

Begin also cut off a Cabinet discussion today on his plans to move his office to East Jerusalem, a predominatly Arab section of the city, as a demonstration of Israel's resolve to retain sovereignty over the area.

Government sources said Begin had not changed his mind about the move to the area captured from Jordan in the 1967 Six-Day War.But several ministers were reported to have concluded that it would be inappropriate to endorse the move formally in the midst of the controversy over the new Jerusalem law, and before Israel has responded to Sadat's note.

Sadat's demands appeared to be a compromise between his desire to avoid ending the talks and his need to demonstrate Egyptian displeasure at the Jerusalem law, passed overwhelmingly Wednesday by the Israeli parliament.

Egypt and the United States contend that the status of Jerusalem must be the result of negotiations set up in the Egyptian-Israeli peace treaty designed to produce a self-governing authority for the Israeli-occupied West Bank of the Jordan River and Gaza. To underline this stand, Sadet suspended the talks in May when the controversial Jerusalem bill was first introduced in the Israeli parliament.

Against the advice of his Foreign Ministry advisers, Sadat agreed to resume the negotiations last month after a meeting in Washington attended by special U.S. negotiator Sol Linowitz, Egyptian Foreign Minister Kamal Hassan Ali and Yosef Burg, the Israeli interior minister and chief autonomy negotiator. Sadat's deciaion was based in part on an offical American assessment that the Jerusalem did not have Begin's backing and would not pass.

After the law's passage and its endorsement by Begin and his party, Sadat was faced with a decision wheter to call off the talks again. His response, as outlined by the well-placed sources today, is an attempt to throw the decision into Begin's lap, thus attempting to portray the Israeli leader as the one responsible for any new breakdown in the talks.

This reflects Sadat's reluctance to suspend the talks outright again himself. In Egypt's assessment, President Carter would be damaged in the American election campaign if his Middle East successes looked as if they were falling through. Sadat and his aides are eager to help Carter, counting on him to increase U.S. pressure on Israel once he is reelected and freed from electoral constraints.

At the same time, however, the sentiment is growing within the Egyptian government that tougher negotiations are needed. Sadat is said to be increasingly irritated by Israeli actions as the talks proceed, including the Jerusalem law, Begin's plans to move his office and continued construction of West Bank settlements.

Those Israeli moves stem from a plan to create as many faits accomplis as possible as the talks go on, Egyptian officials said, predetermining the outcome of the negotiations and making their continuation less and less reasonable.

For this reason, the sources said, Sadat's message also refers to the West Bank settlements and the need to create a better "atmosphere" for continued talks. Egypt's minister of state for foreign affairs, Butros Ghali, often has insisted that the atmosphere created by Israeli settlements and the Jerusalem law makes it difficult for Egypt to persevere in the face of criticism from fellow Arab states that accuse Sadat of selling out the Palestinians for a bilateral peace treaty.

Foreign Minister Ali handed Sadat's message to Israeli Ambassador Eliahu Ben-Elissar today in Cairo as the Egyptian ambassador in Israel, Saad Murtada, was handing it to the Israeli government. The U.S. ambassador in Cairo, Alfred Atherton, also received a copy for transmission to Washington.

The United States is expected to participate fully in the "dialogue" that Sadat has begun with his message, Egyptian officials said. Western diplomatic sources suggested that, in this way, Sadat was in effect replacing the autonomy talks for a time with exchanges of messages, thus relieving Egypt of the need to be seen sitting with its Israeli negotiating partners during the outcry over the Jerusalem law.

This also keeps the situation fluid enough to eliminate the need for another specific Egyptian response if Begin moves his office into East Jerusalem, which seems likely.