President Anwar Sadat said today it would be "useless" for Egypt to resume peace talks with Israel until the Israelis commit themselves in principle to withdraw from the occupied territories.

In strong language, he made clear that his decision to pull the Egyptian delegation out of the talks in Jerusalem was not just a negotiating ploy. The talks are off, Sadat said, until the Israelis understand that they cannot have both peace and the territories.

"The door to peace is not closed," Sadat said. But his comments left the impression that the entire fabric of the negotiations has unraveled and it will take dramatic changes to stitch it back together.

With Sadat and Prime Minister Menacham Begin of Israel now moving away from negotiation and back into long-distance polemics, no such changes appear imminent, at least not without strong action by the United States.

Sadat was speaking at a joint press conference with Secretary of State Cyrus Vance after they met for two hours at the president's rest house on the Nile north of the capital.

Sadat thanked Vance for his "tremendous efforts to bridge whatever differences have arisen" between Egypt and Israel but he declined to say just what Vance and President Carter have done. What Sadat would like them to do is put pressure on Israel to move closer to the Egyptian position, but there has been no indication that the United States is prepared to do that. Vance came here hoping to persuade Sadat to resume the negotiations, but clearly did not succeed.

[A senior American official on the plane carrying Vance from Cairo to Ankara tonight told reporters that he did not see the political negotiations between Egypt and Israel resuming any time in the near future, Washington Post correspondent Michael Getler reported.]

[While conceding that the developments have "hit a bump on the road," the official expressed the belief that the Israel-Egyptian military commitee meetings would probably resume. He found encouragement in the fact that progress has been made to develop a declaration of principles, and indicated the declaration would not necessarily have to deal with the issue of Israel settlements in the Sinai.]

[The official indicated that there was a "real overdoze of emotions on both sides" and countered a report that Sadat was coming to Washington by saying that the United States has not suggested such a trip at this time.]

Vance said little other than that "the U.S. will continue to work with the parties" to try to restore some movement toward peace.

One of Vance's top assistants, Alfred Atherton, who is the department's senior Middle East specialist, remained in Cairo and was expected to go to Israel over the weekend to brief Begin. U.S. officials said Atherton was expected to stay in the Middle East for a while.

Sadat appeared to be in good spirits, but he also seemed exasperated that Israel has not accepted the essential principle of his peace initiative - that peace is obtainable, peace and recognition are there for the taking, provided the Israelis agree to get out of land that is not theirs.

Vance said in Israel yesterday that he really did not know why Sadat had pulled out of the peace talks. American officials in the Vance party said they believed the Jerusalem talks were making progress and that the Egyptian walkout came as a surprise.

But Sadat's comments today showed that it was not the developments in the Jerusalem talks that led to his decision but the cumulative effect of public statements by Begin and Israeli Foreign Minister Moshe Dayan, and the position taken by Israel in last week's military talks here that it was entitled to keep its settlements in the Sinai.

"What worries me really is this," Sadat said. "The while approach to peace is being twisted because we are losing time on discussing, for instance, the settlement problem. We should not lose any time on it because it is a joke. No one can agree for any one to impose settlements on his land and also to continue in arrogance and say that we shall defend them.

He said that "the spirit behind my initiative is not correctly understood among Premier Begin and his aides. For that, I think the peace process would be useless now, to continue on false principles."

Referring to Dayan's call for bargaining and compromise on the territorial issues, Sadat said, "What is the halfway for us? The halfway or us is losing soverignty. No. I this is the form that you want us to work in, no."

When Sadat and Begin emerged from the house onto the sunsplashed lawn to meet the press, Sadat did not wait for the questioning to begin, he spoke a few words of appreciation for the U.S. role in negotiations, and then plunged into his response to the criticism heaped upon by Begin in the past two days.

Referring to Begin's speech in the Knesset yesterday in which he called some of Sadat's proposals "preposterous," Sadat said "anyone who reads his speech can feel that I was right, because they want land, they want security, they want everything, and they are not ready to understand that peace cannot be ahcieved except if it is built on justice."

"We don't seek peace at any price. Not at all. They would be wrong in Israel if they thought of this. Begin in his arrogant way said in the Knesset that he doesn't need the recognition of anyone here. Very well, let us not start commenting on this because this is still the old arrogant way. Today or tomorrow he will see that Israel does not gain by it at all."

The president said that "the minimum for continuing our work" of negotiating peace is a declaration from Israel of willingness in principle to give up the territories, and to grant self-determination to the Palestinians. If Israel does that, he said, there could be swift progress toward peace.

"I'm not talking pressure, or conditions, just putting logic. Can peace be achieved when someone treads on other's land and even proceeds in his arrogance and says he will defend it also, on my land?"

Sadat stopped well short of giving up on peace altogether. He said he asked Vance to convey "certain precise messages" to Carter, a reflection of the growing feeling here that the United States must act firmly to nudge Israel out of its position on the occupied territories if the negotiations are to get anywhere.

And Sadat also restated his agreement to resume the negotiations of the Egypt-Israel military committee. The function of that committee, however, is to negotiate the details of Israel's withdrawal from the Sinai. The commitment to make that withdrawal, which Sadat once thought he had already received, is now at issue. In any case the Israelis have not yet decided whether to continue participating in those talks.

Sadat laughingly declined to reveal what he is planning to say in a major address to the Egyptian Parliament that he is to make on Saturday night. He has often used that forum for his most important policy statements on international affairs.