In a surprise move, Israeli Prime Minister Shimon Peres flew to Morocco today to meet with King Hassan II to discuss Middle East peace prospects, senior Israeli officials said tonight.

The talks, scheduled for Tuesday, will be the most open contact between Israel and an Arab state since the series of meetings between the late Egyptian president Anwar Sadat and former Israeli prime minister Menachem Begin that began with Sadat's historic visit to Jerusalem in 1977 and culminated in the signing of a peace treaty in Washington in 1979.

There was speculation here that the talks could lead to a breakthrough in Israeli-Arab relations. In Washington, U.S. officials described the meeting -- of which the United States reportedly was informed in advance -- as an extraordinary step in Arab-Israeli relations.

Jordan's state television said King Hussein received messages or had telephone conversations today with four Arab leaders, The Associated Press reported, and Agence France-Presse said Hussein met with a special envoy from Hassan tonight, but there was no indication whether the flurry of contacts was related to Peres' trip.

Peres, according to informed Israeli government sources, flew to Rabat late this afternoon in an Israeli Air Force executive jet, accompanied by senior aides and Israeli reporters. Among the aides, Israeli radio said, was Moroccan-born Rafi Edri, parliamentary whip of the Labor Party, who has visited Rabat several times recently.

Officials in the Israeli Foreign Ministry and prime minister's office refused to discuss details of the trip and the military censor restricted reporting of Peres' movements for several hours.

Peres' visit appeared certain to generate strong opposition among hard-line Arab states, which traditionally have opposed any diplomatic contact with leaders of the Jewish state.

However, it is not the first time that Hassan, who has cordial ties with many western governments, has played a role in opening an Israeli-Arab dialogue in hopes of furthering a comprehensive Middle East peace.

He acted as an early intermediary in the Egyptian-Israeli contact that led to Sadat's visit to Jerusalem and to the Camp David peace treaty. He reportedly has met secretly with Peres and other Israeli officials several times, although both governments have consistently denied such meetings have taken place.

Last Nov. 25, both Peres and Hassan said publicly that they would be willing to meet, although Hassan denied the next day having made such a statement. The Moroccan monarch, who is chairman of the Arab League, was reported to have come under intense pressure from rejectionist Arab states following his announcement that he was willing to meet with Peres.

Hassan had been scheduled to visit Washington this week, but last week his government canceled the trip, citing "fatigue." Informed sources in Washington said today, however, that the United States had been advised before the cancellation of the planning for Peres' trip, Washington Post staff writer John M. Goshko reported.

While U.S. officials are understood to consider the Hassan-Peres meeting an extraordinary step in Arab-Israeli relations, the Washington sources said, they do not know enough about the situation to say what it means or make any assessments of its implications for the Middle East peace process.

Apart from contacts between Egypt and Israel, and rumored secret meetings between Israeli leaders and Hussein, publicly acknowledged talks between Peres and Hassan would break considerable new ground in Israel's contacts with the Arab world.

An informed Israeli government source said Hassan's invitation to Peres to visit Rabat appeared intended "to prepare Arab public opinion to some kind of opening with Israel." The source noted that earlier this year, a large delegation of Israelis, including members of parliament, visited Morocco to attend religious festivities.