Shimon Peres, the once and possibly future prime minister of Israel, will speak at the Kennedy Schools this afternoon on the prospects for peace in the Middle East and his controversial call for the convening of an international conference as a means to achieve it.

Peres, leader of Israel's Labor Party, is now serving as foreign minister in Israel's governing coalition. He is in the United States to attend the opening ceremonies of the United Nations General Assembly later this month.

In his speech, which is scheduled for 4:30 p.m. at the Institute of Politics, Peres probably will concentrate on the possibilities of an international peace conference, which would include the Soviet Union and Palestinian representatives, and its implications for the region, said Martin Peretz, a lecturer in Social Studies who arranged Peres's K-School visit.

Under the National Unity agreement reached in 1984, the Israeli Cabinet is divided principally between the liberal Labor Party and its allies and the right-wing Likud bloc. Peres served as prime minister with Likud leader Yitzhak Shamir as his foreign minister through September 1986 when, under the terms of the agreement, they switched roles.

The idea of the international conference is dividing the Cabinet along party lines, for reasons that have as much to do with internal politics as international politics. King Hussein of Jordan is said to want the Soviet Union in attendance at such an "umbrella" conference. He reportedly thinks that he needs their presence to protect him from the wrath of less conciliatory moderate Arab leaders. He has made it clear that he will not meet with the Israelis unless the Soviets have a seat at the conference table.

Likud members fear that the Soviet Union has not earned the right to play a major role in such a conference, and that if it does, it will force the Israelis into an unfavorable settlement. They also fear that Peres and Labor could parlay a successful agreement into domestic electoral success in the next parliamentary elections, scheduled for September 1988.

Peres, who has met often, though unofficially, with Hussein over the years, said he believes that such a conference is the only hope left for peace in the region. He has said that he has received assurances that the Soviets will not seek to play a major role in any conference and that Israel would have the right to leave the conference at any time.