Israel's foreign minister, Yitzhak Shamir, said today that if the Egyptian-Israeli peace process is allowed to continue, the withdrawal of Israeli forces and civilian settlers from the Sinai Peninsula will not be impeded as a result of the assassination of Egyptian president Anwar Sadat.

In the wake of the assassination, Shamir said in brief remarks on his return from an official visit to the United States, all parties involved in the Camp David peace agreement have a special responsibility to work together to fulfill the accords.

Shamir's pledge was underscored by Prime Minister Menachem Begin, who in a message today to Egyptian Vice President Hosni Mubarak, said, "We are confident that the legacy of peace of president Sadat will live on." Sadat, Begin reminded Mubarak, had vowed before his death, "No more war. Let us have peace forever. This is a sacred trust we all have to fullfill."

The official pronouncements seem to have been encouraged by reports from Cairo that the Egyptian constitutional process for presidential succession is moving foward without crisis and that Mubarak has publicly committed himself to continue with the Camp David formula. They came amid undercurrents in the Israeli Cabinet that Israel should initiate high-level discussions with Egyptian officials as soon as possible to clarify some of the enormous implications of the assassination.

Following a 90-minute emergency session of the Cabinet this morning, several Israeli ministers spoke privately of the need for high-level Egyptian-Israeli talks as soon as practical after Sadat's funeral.

The next ministerial-level meeting scheduled between Israeli and Egyptian officials, to discuss the proposed autonomy for West Bank and Gaza Strip Palestinians, is Oct. 21, and some senior Israeli officials suggested that Begin and Sadat's successor probably should meet before then.

The Cabinet authorized Begin to represent Israel at the Egyptian leader's state funeral, but it was uncertain tonight whether Egypt intends to permit heads of government to attend. Begin's press secretary, Uri Porat, noted that the funeral could pose major security problems that the Egyptians might be unwilling to undertake.

Complicating the security problems is the fact that the funeral will be held on Saturday -- the Jewish sabbath -- and that Begin, because of religious strictures, would be required to walk from his overnight Cairo residence to the funeral.

"We asked the Egyptians to find a residence very close the place of the funeral, but up to now we don't even have confirmation that any foreign delegation will be permitted to attend," Porat said.

Sources in the prime minister's office said that Begin feels strongly that his attendance transcends protocol and is a deeply personal and sentimental matter because of the two leaders' many meetings over the last four years. Most of the principal figures of the Camp David accords -- including former president Jimmy Carter, former secretary of state Cyrus Vance and Carter's national security adviser, Zbigniew Brzezinski, on the American side, and former foreign minister Moshe Dayan and former defense minister Ezer Weizman on the Israeli side -- are remote from the peace process, leaving Begin as one of the few original participants still in office.

"If there are any foreign delegations there, no doubt the prime minister will also be there," Porat said.

Begin was also understood to want to demonstrate by his presence at the funeral -- at no small security risk -- that Israel is determined to stick by the Camp David agreements despite the assassination.

Israeli sources said that a return date for Begin was deliberately omitted from the request, to allow the prime minister time for some contact with Egyptian officials while he is in Cairo.

In public statements, Israeli officials continued to express confidence in Egypt's ability to maintain continuity in the peace process. Israeli President Yitzhak Navon declared that, in his talks with many Egyptian officials, "all of them emphasized to me their support of president Sadat's policies with regard to peace with Israel. They saw it as a supreme Egyptian interest."

Privately, the emphasis of some of Begin's advisers was more on a wait-and-see posture, coupled with a determination that Israel should take no precipitious political steps that could upset Mubarak's apparent resolve to continue Sadat's policies.

"Obviously, this assassination raises questions about whether the Arab world is in a stable enough condition to make peace with Israel. But we have no choice, after all the sacrifices we have made for peace, but to sit tight and see what happens," a Begin aide said. He said it probably would take an overt act of hostility by the new Egyptian regime, such as seeking rapprochement with rejectionist Arab states or supporting an anti-Israel resolution in the United Nations, to stimulate Israel to the point of reconsidering its treaty obligations.

As the shock of Sadat's death became more subdued in Israel because of the Yom Kippur holiday -- the holiest day in Judaism -- militant Palestinian nationalists in the West Bank celebrated the assassination as the end of the Camp David peace process.

Ramallah Mayor Karim Khalif said, "It is not a loss to the Egyptian people nor the Arab world . . . ." Similarly, Anabta Mayor Wahid Hamdallah said, "We have heard that Begin and Reagan were shocked on hearing the news of Sadat's death, but we, frankly speaking, were happy to hear the news item."

Nablus Mayor Bassam Shaka said that the will of the Egyptian people had been assassinated by Sadat long ago, adding, "We hope that the Egyptian people will restore their position within the patriotic and national trench in order to liquidate the imperialist policy and contribute to the achievement of the legitimate rights of the Palestinian people."

Some Palestinian nationalist leaders held parties to celebrate the assassination, and shopkeepers in Bethlehem and Nablus distributed free candy to passers-by to mark the event.

Ultranationalist Jewish settlers also interpreted the assassination as an end to Camp David, with Yisrael Harel, chairman of the Council of Settlements (of the West Bank and Gaza Strip), saying, "The root of the Sadat phenomenom is that the Arabs oppose our existence, not our holding of territory. Therefore the assassination of Sadat is the assassination of peace, definitely."

Rabbi Meir Kahane, leader of the extremist Jewish Defense League, said, "What is this mourning and sense of national tragedy? Why does the government of small men and vision not grasp the greatness and miracle of this day? The death of Sadat, the enemy of the Jewish people, is divine intervention meant to save the state of Israel from both its enemies and itself."