Egyptian President Hosni Mubarak took sharp issue yesterday with what he termed the Reagan administration's policy of inaction in the Middle East, calling it "almost a defeatist approach" and arguing that it was based on the wrong premises.

In an emotional speech before the National Press Club, the Egyptian leader said the United States remained uniquely placed to play "a pivotal role" in helping to achieve a settlement of the Palestinian issue, and he appealed for a radical change in the present wary American attitude toward Egypt's efforts to get the peace process moving again.

"Some have suggested that the United States should wait and see how things develop. In effect, the proponents of this view advocate inaction as a line of policy," Mubarak said. "I beg to differ. This is almost a defeatist approach based on a series of wrong premises."

Later, he added: "You cannot say, 'I am waiting until the parties agree on everything before I step in.' The role of a great country like the United States is not simply to endorse what was agreed upon; rather, it is to help the parties reach agreement."

Mubarak also made clear that he was still not ready to send his ambassador back to Tel Aviv -- an issue of major concern to Congress and the administration -- until Israel agreed to submit an unresolved border dispute to international arbitration. But he said he thought a solution was "on the way now."

Showing signs of frustration with the administration's lukewarm reaction to his three-stage peace plan aimed at bringing about direct Arab-Israeli talks, the Egyptian leader said he had asked President Reagan during their talks Tuesday to invite a joint Jordanian-Palestinian delegation to come here, "or anywhere else," to explore the chances for a settlement.

"Such a dialogue," he said, "would not only clarify different positions, but most importantly, it will reinforce the momentum for peace."

This, he told a questioner after his speech, was "the minimum" the United States should do to help put new life into the dying Middle East peace process.

Administration officials briefing reporters on the Mubarak initiative have repeatedly said Washington is not interested in doing anything that smacks of "prenegotiating the American position" toward new peace talks or that amounts to a recognition of the Palestine Liberation Organization before it has formally recognized the existence of Israel by endorsing U.N. Security Council Resolution 242.

Mubarak apparently sought in vain to convince Reagan that the United States should accept the Feb. 11 agreement between King Hussein of Jordan and PLO Chairman Yasser Arafat as an "unequivocal and unambiguous" statement of the Palestinians' acceptance of this resolution, which the United States insists must form the basis of any new U.S.-supported Arab-Israeli negotiations.

The Jordanian-Palestinian agreement backed all U.N. Security Council resolutions on the Middle East but failed to mention 242 specifically.

Resolution 242, adopted after the 1967 war, calls for Israel to withdraw from occupied Arab lands in return for a guarantee of peace and secure borders. But it makes no mention of the Palestinians as more than a "refugee problem."

Mubarak said Arafat's signature on the Feb. 11 accord represented his "firm commitment" to the resolution, saying "there was no need for a specific mention of a certain document."

Earlier at a meeting with editors and reporters of The Washington Post, Mubarak said he was sure the PLO was ready to accept Resolution 242 "clearly" and would do so "whenever they are secure they are going to have something."

Mubarak said that Reagan had promised "to do his best to do something to use this initiative," but that Mubarak's plan for a three-stage negotiating process aimed at starting direct Arab-Israeli talks "needed to be discussed within his administration."

In reply to a question about what he would do if the administration refused to deal with a Jordanian-Palestinian delegation, Mubarak revealed some of his own uncertainty -- and frustration -- about where his initiative to start a three-stage negotiating process was leading.

"Frankly, I don't know," he said. "I can't tell you. You are going to lose. We are going to lose. Terrorism will start and problems will be much more complicated in the area. That's why I'm urging the United States to make a dialogue, please."

At the press club luncheon, Mubarak avoided giving a straight reply to the same question about Reagan's reaction, saying that he had only come to "exchange views" with the President and that he was "not seeking decisions now."

"I explained to the president this golden opportunity and I dealt with the Jordanian-Palestinian delegation as something we need now."

Mubarak repeatedly pleaded for the United States to open what he was careful to call "a dialogue, not negotiations" with a Jordanian-Palestinian delegation, arguing that U.S. concern about not talking to the PLO was misplaced since there was no way of ever distinguishing for sure who might be a member.

Mubarak said he had also not sought, or received, any immediate commitment from Reagan regarding Egypt's request for an additional $1.8 billion in U.S. aid over the next two years.

On the contested border dispute at Taba, an 800-square-yard stretch of beach on the Gulf of Aqaba, Mubarak said Israel had made it "a national issue" in his country by insisting on holding on to it, even though before the 1956 Arab-Israeli war it had belonged to Egypt and the Israelis had then given it back.

"Let them send it to arbitration to finish with this stupid problem because it became a national issue" in Egypt, Mubarak said.