Former secretary of state Henry Kissinger, here on the first leg of a fact-finding tour of six Middle East countries, has ended his talks with Egyptian President Anwar Sadat in disagreement over when Jordan should become involved in any new peace negotiations.

Kissinger, who made an unscheduled one-day side trip to Somalia today, told reporters at a press conference yesterday that it is time for Jordan's King Hussein to become directly involved in the Camp David talks.

"If I understand Camp David, Jordan was invited to participate," Kissinger said. "If the negotiations of the West Bank show some progress, then it would seem that if Jordan desires it, it could play a role in that evolution."

On Monday, Sadat expressed a different opinion after spending the afternoon with the former American Middle East peace negotiator.

"I have already said that King Hussein has a role in the Camp David agreements and a very big role," Sadat said, adding, "But I advise that he join only after we reach an agreement upon the full autonomy" for the Israeli-occupied West Bank and Gaza.

Kissinger indicated that he intends to report back to President-elect Ronald Reagan on his talks with Middle East leaders, but he sough to scotch speculation he will become a special ambassador to the Middle East in the new Republican administration, taking over from Sol Linowitz.

"I am available for advice and for specific assignments of limited duration," Kissinger said. "I do not think I would be most useful in the detailed implementing negotiations of the autonomy talks."

Sitting in with Kissinger on his meetings with Sadat and other top-level Egyptian officials was the chairman of Columbia Broadcasting System, Inc., William Paley, 79, who shrugged off speculation that he might replace Linowitz if Kissinger didn't.

"I've had no offers from the Reagan administration," he said. "This is a private visit."

[In New York, a spokesman in Paley's office said Paley and Kissinger had planned the trip last July and that it was solely for "information and pleasure." While the two men are using a CBS plane for the trip, Paley was paying for it privately, the spokesman said, and added: "It has no political significance at all."]

It was unclear if Kissinger was pushing for the so-called Jordanian option at Reagan's prompting. If so, this could develop into the first major issue separating the two presidents.

Most Arab nations, including Jordan, vehemently have opposed the Camp David accords initiated by the Carter administration that led to the 1979 peace agreement between Israel and Egypt. Subsequent talks between the two nations have stalled over the issue of granting autonomy to the 1.2 million Palestinians living in the Israeli-occupied West Bank and Gaza strip.

The new Reagan administration has indicated it would like to set the Camp David peace process moving again by getting Jordan involved.

[In Washington, Reagan's newly appointed national security adviser, Richard V. Allen, met Tuesday with the commander-in-chief of the Jordanian armed forces, Sharif Sharaf. An embassy spokesman said the talks touched on "all possibilities for strengthening bilateral Jordanian-American relations" and the Middle East situation, but he refused to say whether they also had discussed the possibility of Hussein's making a state visit to Washington shortly after Reagan's inauguration.]

From Washington's perspective, bringing Jordan into the negotiations would give Camp David a broader appeal to the rest of the Arab world. Jordanian support also might lead to acceptance of the accords by the Palestinians, who also have opposed Camp David.

Sadat, however, fears that Hussein would participate in the autonomy talks only in an effort to gain control of the West Bank for Jordan.

Among Egyptians, from top officials to the man in the street, there is hope that Kissinger will become part of the Reagan administration and be again involved in the Middle East peace process. He is remembered with affection as the American who pioneered peace between the Arab states and Israel under Presidents Richard Nixon and Gerald Ford.