Egyptian President Anwar Sadat met for almost three hours with Israeli opposition leader Shimon Peres in this alphine city yesterday, and afterward told reporters that the "peace process has gained momentum" as a result of the talks.

Sadat termed their discussions - the first contact between the Egyptian president and a major Israeli political figure since political talks on a peace settlement broke down last month - "a new step in our cooperation along the road to peace and security for both nations."

Even before their talks, Sadat told reporters on his arrival here yesterday he felt there is now "sufficient momentum in the present peace initiative to achieve a final settlement."

Both men publicily sought to dispel any notion that the unusual meeting was meant to drive a wedge between the Israeli government of Prime Minister Menachem Begin and the opposition Labor Party headed by Peres.

Peres pointed out that Begin had been informed ahead of time about the meeting, which was arranged by Austrian Chancellor Bruno Kreiky about a week ago but kept a secret until it was announced Friday. He said the Israeli prime minister "was glad about the meeting and encouraged it."

"In foreign affairs, we are just one government," Peres said. And he added: "I am not a negotiator."

Sadat, under questioning, said that Peres had brought no new messages from Begin nor were new proposals exchanged. Rather, both men described the meeting as a thorough review of where things stand and each other's position, and as a continuation of the talks that the two men began in the Israeli parliament late last year after Sadat's journey to Jerusalem.

Sadat would not offer any specific timetable when asked about the re- sumption of the political talks that were broken off by Egypt. Sadat pulled his negotiating team out over what he viewed as Israeli intransigence on evacuating occupied settlements and military bases in the Sinai and West Bank of the Jordan River and on the Palestinian question.

Sadat said yesterday that U.S. negotiator Alfred Atherton would arrive soon in the area to resume shuttle diplomacy between the two countries and that after he hoped "something would materialize."

Peres, in interview with reporters elsewhere in recent days, has expressed the view that Sadat was too isolated emong Arab moderates and badly needed and ally, especially King Hussein of Jordan, to help solve the West bank issue.

Asked about this yesterday, Sadat rejected the notion, claiming that he doesn't feel isolated, that he is not influenced by attacks from "certain Arab leaders," and that he would continue what he views as "his sacred mission" even "if it should be my last as president."

As for King Hussein, Sadat said the Jordanian ruler has shown support and "I told him to take his time and when he is ready we shall welcome him to the Cairo conference."

Despite Sadat's comments that this meeting had nothing to do with seeking alternatives elsewhere in Israeli politics for his position, the Egyptian president's current trip to the United States and Europe, in fact, puts him in touch with virtually every influential group that could conceivably put pressure on the Israelis.

In the United States, he met with the president and congressional leaders and Jewish community leaders in West Germany, he met with Chancellor Helmut Schmidt, a powerful figure within the nine-nation European Economic Community which has already made statements that Jerusalem does not like.

The Austrian chancellor, who was born a Jew but has long since disavowed his religion, is a major figure in the Socialist International, as is Peres, who represents Israel's version of the Social Democrats.

Sadat left here yesterday for Bucharest, where he will meet with Romanian President Nikoali Ceaucescu - a central figure behind the scenes who helped arrange the initial meeting between Sadat and Begin last fall.

Though Romania is a member of the Soviet-led Warsaw Pact, the country is a maverick in its foreign policy and is the only Soviet bloc country that has relations with Israel. The Isrealis value those relations and thus the Romanian leader becomes one more potential pressure point for Sadat's journey. He is also visiting France, Italy and the Vatican.

Kreisky, in effect, used his position within the socialist movement to bring Sadat together with Peres, who was in West Germany earlier this week attending the Socialist International meeting.

Since Austria was on Sadat's tour, the chancellor explained to reporters that he thought it would be good to get the two men together and Sadat agreed.

Peres' views on foreign policy are seen as aligned with Begin on most points. The Labor Party leader and former defense minister, however, is generally held as taking a softer line on the conditions of return of the West Bank than does Begin.

While in West Germany, Peres also met with Chancellor Schmidt and reportedly asked Schmidt if he and the European community would not mind being quiet instead of issuing declarations on Middle East positions because this, in the Israeli view, tends to encourage Arab extremists who think Europe can pressure Israel.

Peres also reportedly expressed dismay at the recent sale of missiles to Syria by a French company that is joined with a West German firm in production of the missiles.

West Germany's controversial conservative leader Franz-Josef Strauss is on the board of governors of the West German firm, and Sadat met with him earlier yesterday before he left the West German resort of Berchtesgaden for the 10-minute helicopter flight to Salzburg.