The Mideast peace summit meeting of President Carter and the leaders of Egypt and Israel, which had been expected to take place next month, will have to be set back until December or next year, offficials of the three countries said yesterday.

That change in the timetable became known as negotiators ended the latest round of talks on a Palestinian autonomy agreement. While asserting that the two-day session here had produced "encouraging signs of progress" on some issues, the negotiators also conceded that considerable work remains before the point is reached where a summit meeting could wrap up an agreement.

At a news conference, Sol. M. Linowitz, the U.S. mediator in the talks, said a summit this year "may still be in the cards." But he also said he would be "very surprised" if the next round of autonomy negotiations, set for Nov. 17 in the Middle East, "could be the only one required prior to a summit."

Egyptian Vice President Hosni Mubarak, here for separate meetings with Carter and other administration officials, was even more specific. Following a meeting with Secretary of State Edmund S. Muskie, Mubarak told reporters that since very careful preparation is required for a successful summit, his government doubts that the meeting could be scheduled before January.

Since Egyptian President Anwar Sadat has been the principal in the negotiations most insistent on holding a summit, this shift in the Egyptian sense of urgency seemed to make it unlikely that the meeting will be held before next year.

Reliable sources said the Egyptian change of attitude appeared to be dictated by Sadat's concern that the Iran-Iraq war has introduced too many elements of uncertainty into the Mideast situation and by increasing belief in Cairo that Republican Ronald Reagan will be elected president Nov. 4.

While conceded that these are factors in Sadat's calculations, U.S. sources insisted that the main reason for setting back the summit timetable was a growing realization by all parties that the negotiations still have a long way to go before it would be realistic to stage a summit with any hope of success.

But, these sources continued, that fact should not be taken as a sign that the talks here this week were marked by more of the stalemate that for 19 months has impeded the attempt to work out a formula of limited self-government for the Palestinian inhabitants of the Israel-occupied West Bank and Gaza Strip.

In fact, the sources said, the latest round, which came after the talks had been in limbo for almost five months, was marked by what one called "more constructiveness and more imagination in trying to bridge the differences" than has been evident at any point in the past.

Linowitz, although refusing to discuss specifics, said, "There has been progress on several issues moving closer to agreement." The sources said privately this progress had come primarily on such questions a future control over scarce land and water resources in the occupied territories and on defining the powers of the Palestinians' self-governing authority.

According to the sources, the major areas of disagreement still involve the questions of how much military control Israel will be able to exert in the disputed territories to protect its security and whether Palestinian residents of East Jerusalem, which is outside the jurisdiction of the proposed accord, will be able to vote for the self-governing authority.

In preparation for this week's round, Linowitz had prepared a "memomorandum of agreement" to solicit suggestions from the Egyptians and Israelis and to serve as a basis for negotiations. He said yesterday that, based on the points of accord and disagreement that emerged in the talks here, he now will prepare a revised memorandum.

That will be forwarded to the two other governments for their comments and suggestions, and these documents in turn will be the focus of discussion at the Nov. 17 meeting. Linowitz said it was not yet clear whether that next meeting will involve him and the other two delegation heads, Egyptian Foreign Minister Kamal Hassan Ali and Israeli Interior Minister Yosef Burg, or be conducted at a lower level.

Mubarak, who also conferred yesterday with Defense Secretary Harold Brown, said Egypt had renewed its offer to permit U.S. use of Egyptian base facilities to help defend the countries of the Persian Gulf region. He also said that about 1,400 American troops who will go to Egypt later this year for joint training exercises with Egyptian forces will be there for as long as three weeks.