LONDON, MARCH 1 -- Secretary of State George P. Shultz met with King Hussein of Jordan here today to discuss the U.S. peace plan, bringing no commitment from Israel's badly divided government to support it.

After five days of commuting between Jerusalem and three Arab capitals, Shultz conceded he had not yet won either Israeli or Arab backing for the plan, but he pledged to continue working for a breakthrough.

"If I had to describe the situation, I would say no one has signed up to our proposals but everybody wants us to keep working. So we'll keep working," he said before boarding his plane at Tel Aviv airport.

In Jerusalem, a senior Israeli official said both Israel and Jordan had rejected parts of the U.S. plan but still wanted Shultz to continue his mediation efforts.

Yossi Ben Aharon, director general of Prime Minister Yitzhak Shamir's office, told a group of visiting American Jewish leaders that Shamir had rejected "an early date certain" for negotiations on the final status of the Israeli-occupied territories.

"We should not be stampeded into discussing sovereignty today," Ben Aharon said. "They want us back to the 1967 {boundary} lines, which is a mortal danger to us."

Shultz said he would decide whether to return to the Middle East immediately after the NATO summit meeting once he has talked to President Reagan in Brussels Wednesday morning. His aides said there was a good chance he would return to the region.

Despite the lack of immediate concrete results, Shultz seemed pleased with the way his talks with Arab and Israeli leaders have gone so far, except for the refusal of any Palestinians to meet with him.

He said all his discussions had been "very substantive and direct and to the point," and that as a result of the Palestinian unrest in the occupied territories over the past three months, "people's minds are more open."

Shultz said Hussein, who is here for medical treatment, is "a very critical factor" in the negotiations because of his standing as a "longtime important figure" in the region.

An aide said Shultz's three hours of talks with Hussein on the peace plan had been "serious," and that "nobody said yes or no."

{A Jordanian Embassy statement issued in London said Hussein "asserted to Secretary Shultz Jordan's rejection to any partial interim or unilateral settlement," Reuter reported.}

Shultz held a fourth and final round of separate discussions with Shamir and Israeli Foreign Minister Shimon Peres last night with no sign he had won any major concessions from Shamir, who has expressed the greatest reservations about the U.S. plan.

A Shultz aide confirmed that Shultz has been discussing the possible attendance of all five permanent members of the U.N. Security Council -- the United States, the Soviet Union, China, Britain, and France -- at an "international event" to start the negotiations.

Jordan and Syria insist that talks be held under the auspices of the five, but Shamir has rejected this approach.

Shultz had suggested that the United States and Soviet Union serve as joint hosts for the opening session of a "nonauthoritative" international conference that would allow the parties directly concerned to move immediately to bilateral talks.

The idea of including the other permanent Security Council members is apparently aimed at gaining Arab backing; keeping the conference "nonauthoritative" is aimed at gaining Shamir's support.

The U.S. plan tentatively calls for initial talks on interim autonomy for the 1.5 million Palestinians living in the Israeli-occupied West Bank and Gaza Strip. These talks on interim arrangements involving Israel, Jordan and the Palestinians would be followed by negotiations starting in December to determine the final status of the occupied territories, including the Syrian Golan Heights, that Syria would attend as well.

Shultz indicated to reporters on his plane to London that he was deeply disappointed by the failure of the Palestinians to meet with him in Jerusalem.

He said he had made every effort to talk directly to them with "carefully crafted" statements directed specifically at their concerns.

He indicated he had chosen the American Colony Hotel in Arab East Jerusalem to meet a Palestinian delegation last Friday because it was a site where a U.S. secretary of state "has never been ready to go before." Under pressure from the Palestine Liberation Organizaton, all 15 invited Palestinians boycotted the meeting.