A high-ranking Palestine Liberation Organization official would say little tonight about the crucial talks between President Reagan and the Saudi and Syrian foreign ministers pending a full report on the White House meeting.

But based on press accounts of the meeting, the official, who asked not to be named, said that if the "discussions concentrated on Israel's withdrawal from Lebanon, that itself is encouraging and reflects what we hope for."

In the past, he said, emphasis has been laid solely on PLO withdrawal from West Beirut, the capital's predominantly Moslem sector that has been under Israeli siege for the past five weeks.

The official said that every nuance of the White House talks with Prince Saud Faisal of Saudi Arabia and Syria's Abdal Halim Khaddam requires close scrutiny. Under discussion, he suggested, had been PLO and American "exploration" of how far each side would go toward entering into a dialogue.

Khaled Hassan, a close associate of PLO chairman Yasser Arafat, will stay on in Washington "for several days," the official said, apparently to clarify details of the Arab ministers' talks.

The official described as "not very sensible" suggestions that the PLO is now willing to recognize Israel's right to exist in exchange for American recognition of its own claim as the Palestine people's sole legitimate representative.

What is involved, rather, he indicated, are new formulations that eventually could go as far as including the PLO in global negotiations about the future of the Middle East.

Ever since 1975, as a result of a secret protocol between the United States and Israel, the American government has refused to deal with the PLO on substantive diplomatic and political questions.

Specifically irritating to the PLO has been American insistence that the guerrillas accept United Nations Security Council Resolution 242, which refers to the Palestinian question solely as a refugee problem.

The PLO insists on the Palestinian people's right to a national homeland, although over the years it has dropped its original claims to Israel proper in favor of setting up an independent state on any land relinquished by Israel--meaning the West Bank and the Gaza Strip, both occupied by the Jewish state in 1967.

In an interview with The Washington Post before the White House meeting, Salah Khalaf, a key Arafat lieutenant better known as Abu Iyad, suggested that if Resolution 242 were involved in the Washington talks it would mean "the same old position--that nothing had changed."

Asked what might be involved in Washington, he said, "Maybe a decision to stop an Israeli attack against Beirut, but definitely they are not going to bring us a Palestinian state."

Meanwhile, in Beirut, the present cease-fire--the sixth since Israel invaded Lebanon June 6--held with some notable exceptions.

Israeli warplanes zoomed low over besieged West Beirut, causing panic in late afternoon. Earlier in the day, Israeli and Palestinian gunners exchanged fire in and around the much-damaged southern suburbs.

At mid-morning six artillery rounds landed near the Israeli checkpoint in the port of Beirut, according to state-run radio, temporarily interrupting activities on the docks.

More than 24 hours after the kidnaping of David Dodge, the acting president of the American University of Beirut, his whereabouts and the identity of his abductors remained unknown despite intensive efforts by a variety of Lebanese and Palestinian security forces.