The leadership of the Palestine Liberation Organization today defended the legitimacy of the Palestine National Council that is meeting here and dismissed its dissident PLO critics as minor and unimportant.

Salim Zaanun, the vice chairman of the PLO's "parliament in exile," said at a news conference that despite Syrian pressure and threats, 261 of the 374 active delegates are here, 11 more than the 250 needed for a quorum.

"We are very proud of those people who defied the threats and came to this meeting," Zaanun said. "By and large the courageous prevailed and are at this meeting. We don't care about the others."

Later, the council voted to oust its speaker, Khalid Fahoum, who had tried to block the session and held a news conference in Damascus, Syria, charging that it was illegal.

"The Amman meeting was theatrical and a farce, and all resolutions that may be adopted there are illegal and will not be carried out by most groups of the Palestinian resistance," Fahoum said at the news conference.

The council voted overwhelmingly to oust Fahoum, then elected Abdel Hamid Sayeh to replace him. The votes were seen as part of a show of defiance by Arafat and his supporters to demonstrate that they had overcome Syria's efforts to block the meeting.

Zaanun said the PLO rebels who have called for the ouster of Chairman Yasser Arafat are "only a small band that the Syrian regime can collect." He added that they will always be welcome to rejoin the Arafat-led PLO. He also predicted an eventual reconciliation between the PLO and Syria, when, he said, "there will be no talk of dissidents."

Establishing the legitimacy of the 17th session of the Palestine National Council and of Arafat's continuing leadership of the Palestinian movement was the first order of business as the delegates and hundreds of observers gathered for the opening night meeting in the Jordanian capital yesterday.

Arafat and his loyalists are in a fierce struggle for supremacy on the Palestine issue with Syria and the Syrian-backed PLO rebels. Expelled from Lebanon last year by the rebel forces, Arafat has gambled that by convening this meeting in defiance of Syria he could demonstrate that he still retains the loyalty of most Palestinians.

There have been numerous predictions that Arafat's decision to convene the meeting could have historic consequences, cementing the split in the PLO that developed rapidly after Israel's 1982 invasion of Lebanon and the destruction of the PLO's base there. In this view, the permanent split would leave the PLO with two distinct rival wings: the moderates under Arafat who are willing to explore peace negotiations with Israel, and the radical forces aligned with Syria that remain committed to the principle of armed struggle.

Whether that will be the outcome of the 17th Palestine National Council meeting is not clear. What is clear, however, is that Arafat and his followers continue to hold open the possibility of an eventual reconciliation with Syria and the PLO dissidents.

While their claim to a legitimate quorum at this meeting has been challenged, the Arafat loyalists apparently believe that by going through with the session, they already have demonstrated the legitimacy of their leadership of the PLO, and that Syria will eventually be forced to acknowledge this, clearing the way for a full reconciliation.

Zaanun acknowledged at the news conference that the PLO had fallen short of the 270 delegates it had hoped would attend the Amman meeting. He blamed this on the Syrians, who, he said, had prevented some delegates from flying here from Beirut and the countries of the Persian Gulf.

Zaanun expressed little concern over reports from Damascus that the PLO dissidents had denounced the meeting and planned to form their own organization. Referring to the fighting last year around Tripoli, Lebanon, he said, "Those people who shot at their own Palestinian people will do anything. We don't care."

The meeting here is expected to last until the middle of next week. The PLO delegates will hear a report on Saturday by Farouk Kaddoumi, head of the PLO's political department, and then begin work in committees on a number of resolutions and statements to be presented to the conference for adoption.

Last night, King Hussein of Jordan told the opening meeting of the Palestine National Council that it was time for "a new approach" to the decades-long Israeli-Palestinian conflict.

In unusually blunt language, Hussein scolded the PLO and the Arab world in general for dissipating their energies on internal disagreements while Israel tightened its grip on the occupied West Bank and Gaza Strip. He said only the PLO could decide its own future, but urged the formulation of a joint Jordanian-Palestinian initiative for peace negotiations with Israel under the auspices of a U.N.-sponsored international conference.

The Los Angeles Times reported the following from Jerusalem:

Israeli officials said remarks by Hussein and Arafat at the meeting in Amman had given them little reason to change their view that no breakthroughs are imminent in the stalled Middle East peace process.

"My feeling is that if we do make a breakthrough, it will not be because of speeches and conferences," commented Abba Eban, former ambassador to the United States and now chairman of the parliamentary foreign affairs and defense committee in a Israeli radio interview.

Uri Savir, spokesman for Israeli Prime Minister Shimon Peres, said Peres "expressed doubts as to whether the PLO will take up King Hussein's offer of a diplomatic path to resolve the Arab-Israeli conflict."

The spokesman quoted Peres as saying, "Past experience has shown that divisions in the Arab world, including the PLO, have only sparked competition over a radical line."