President Hosni Mubarak, preparing for the arrival here Monday of Secretary of State George P. Shultz, told reporters yesterday that Egypt regards the Palestine Liberation Organization as the sole representative of the Palestinian cause.

Speaking to reporters in El Arish, Mubarak said that "as far as Egypt is concerned, the Palestine Liberation Organization is the sole representative of the Palestinian people until now according to the Rabat Arab summit resolution."

Mubarak, at the same time, urged the PLO to "coordinate to create a linkage with King Hussein of Jordan so that the Americans could start working" on new Middle East peace talks.

Although Egypt was a part of the 1974 agreement in Rabat, Morocco, its leaders in recent years had avoided using that document's description of the PLO as "the sole, legitimate representative" in order to facilitate the participation of West Bank Palestinian leaders in the peace process.

The Egyptian Foreign Ministry's chief spokesman, Raouf Ghoneim, said yesterday, however, that "this does not represent any change in Egyptian policy."

Pressed today for further explanation, Ghoneim said that what Mubarak meant to say was that the PLO represents "the only organized sort of representation" for the Palestinians at the present time.

"There is no other organization. They are the only ones," he said.

Mubarak said he regarded Shultz's visit as "very important" and said an agreement on an Israeli withdrawal from Lebanon was "vital" to rebuilding "the image of the United States in the region."

Shultz left by airplane Sunday evening from Andrews Air Force Base for Cairo, The Associated Press reported. He also is to visit Lebanon and Israel and possibly Syria and other countries.

Mubarak's comments in advance of Shultz's first visit to the region as secretary of state seemed in keeping with the reaction so far of America's Arab allies, who are increasingly questioning U.S. credibility and political willingness to use leverage with Israel either to forge a settlement in Lebanon or to stop the expansion of Jewish settlements on the West Bank.

Whether intended as a signal to Washington or not, Mubarak's comment about the role of the PLO seemed to be in line with the probable general Arab reaction to President Reagan's suggestion the Arab states should strip that organization of its mandate.

Mubarak had avoided restating the Rabat endorsement earlier this year when PLO Chairman Yasser Arafat asked him to do so.

In an interview with The Washington Post in January, Foreign Minister Kamal Hassan Ali, asked to comment on Arafat's request, said that Egypt considered the PLO as "having an essential role but not a sole role" in the peace process.

Egyptian officials have said Egypt was holding off from such a blanket endorsement of the PLO to support the Reagan initiative, which envisages Hussein acting as the chief negotiator on behalf of the Palestinians in new U.S.-sponsored peace talks.