The Middle East summit passed its 10th day yesterday as White House press secretary Jody Powell declared that "more flexibility" is essential if the marathon talks are to reach the American goal of producing a "framework" for an Arab-Israeli peace.

While Israeli Foreign Minister Moshe Dayan met first with President Carter and then with Egyptian President Anwar Sadat, Powell responded to a sudden surge of optimistic reports about the likely outcome by attempting to lower expectations about the summit's conclusion.

In a carefully worded statement agreed to by the American, Israeli and Egyptian delegation to the summit, the press secretary said:

"As we said before coming to Camp David, our goal is to produce a frame-work for reaching peace in the Middle East. There has been some progress and some flexibility, but we do not yet have a framework. More progress and more flexibility are essential if that goal is to be achieved."

But he continued to insist that the talks at nearby Camp David were not stalled. Other sources said that the pace of meetings among officials of the three delegations was at least as intense as it had been Wednesday, when Powell was visibly more upbeat in his description of the conference's progress.

Some of the meetings held over the past two days, while not announced by Powell, represented strong indications that the delegations were involved in final negotiations over detailed legal points of a concluding agreement. Osama al-Baz, counselor of the Egyptian delegation, has been meeting with Aharon Barak, former Israeli attorney general who has been named to Israel's supreme court.

Sadat has not met with Israeli Prime Minister Menaghen Begin in a negotiating session since Sept. 7. His session with Dayan yesterday was described by one informed source as being part of a deliberate strategy to keep the two top leaders apart at this detailed stage of negotiations and prevent the hard bargaining that is going on now from being translated into personal tensions between the two leaders.

A U.S. official who asked not to be named said that Sadat and Begin both appeared to be in good health. Another source said that fatigue had begun to wear down some of the negotiators and suggested indirectly that a weekend respite might be a welcome break before the final decision on the conference outcome has to be reached.

Powell again refused to give any indication when the conferece will end, putting a damper on hopes within the large press corps covering his daily briefings that the conference would end by sundown today, when Begin will observe the Jewish Sabbath and abstain from negotiating for 24 hours.

While no requests for network time have been made, one U.S. official said yesterday that a television address to the nation by Carter to conclude the summit was among the options being considered by the White House.

Wednesday night, Carter met for 35 minutes with Israeli Prime Minister Menachem Begin, and other U.S. officials met with their Israeli counterparts. Yesterday morning, the president took what was described as an hour-long "working walk" with Sadat and later in the day met again for an hour with the Egyptian leader. But there were no meetings involving all three leaders, who have now gone a week in the presidential retreat since their last formal meeting.

While Powell clearly sought to dampen the new cycle of optimism that emerged here in the last few days, he stopped far short of suggesting that the conference is near collapse and might produce nothing of significance.

He said the danger still exists that the negotiations will not produce the American goal of a "framework for peace." But, asked if he meant to say that a failure was still possible, he added, "If you come short of that [framework], what that eventually amounts to, I have no idea."

"Framework for peace" is a phrase used by administration officials to describe the objective of the talks. Essentially, it means agreement on general principles and procedures for a Middle East peace treaty that would allow the resumption of direct Arab-Israeli negotiations over the details.

In the past, Egyptian-Israeli negotiations have broken down over attempts to translate general understandings of objectives into specific principles for a peace treaty. But Powell made clear yesterday that while the three delegations at the summit were exchanging written documents and refining language for a concluding statement, they had not, reached agreement on several specific issues involving much more than the wording of an agreement.

I was speaking in the content of at least some reports which seem to me to imply. . . the idea that somehow we have made it and the only question remaining is just fleshing out the picture of success," he said. "I wish that were true. It is not true."

What the remaining major sticking points are that have bogged down the conference remained unknown here yesterday. But Powell, and Israeli officials in separate comments, strongly denied one news report that Begin had agreed in principle to an Israeli withdrawal of the occupied territory on the West Bank of the Jordan River.

Israeli withdrawal from the West Bank and other occupied territories is a key issue in the talks, as are future arrangements for Israel's security in the event of a withdrawal and a solution to the Palestinian problem. In the past Powell has suggested that important differences remain on all of these issues.

While Powell deliberately sought to dampen the optimism of the last few days, he once again cautioned reporters to avoid "an extreme" of optimism or pessimism and emphasized that "a considerable amount of uncertainty" still surrounds the talks.

"We are not in a stalemate and we are not at a de facto end of the conference in which we are just looking for a way to end it gracefully or something," he said.

Powell said no deadlines have been set for an end to the summit and that it will go on as long as the participants consider it productive. He refused to speculate on when the conference will end and most reporters here gave up trying to guess.

On Wednesday, the conventional wisdom here was that the talks would conclude by today. That no longer was certain, and if they do not conclude by today they would almost certainly go on at least until Sunday because Begin will not conduct business on Saturdays, the Jewish sabbath.

Powell stuck by his description of Wednesday that the conference is in its "final stages," but with an added qualifier:

"The final stage could be the longest stage."