JERUSALEM, SEPT. 21 -- An influential Palestinian professor considered a political moderate by his fellow Arabs was badly beaten today on the campus of Bir Zeit University, a few days after it was disclosed that he and other Palestinians had met with representatives of the Israeli right wing.

Sari Nusseibeh, an assistant professor of Islamic philosophy, was attacked this morning by four or five masked men who pounded him with sticks and bottles and hit faculty members with him who came to his aid, university officials said. He was treated at a hospital for a broken arm and deep head cuts and released tonight.

Nusseibeh was the second Arab resident of Jerusalem to be attacked in recent weeks by Palestinian extremists. Newspaper editor Hanna Siniora's car was burned and threats were made on his life after he announced he would become the first Arab to run for the Jerusalem City Council in next year's elections. He since has said he is reconsidering his decision.

Last week, Faisal Husseini, a political activist and chairman of a nonprofit research and cultural society, was arrested without charge for the third time in six months. An Israeli judge is reviewing his detention.

All three have affiliated themselves with the outlawed Palestine Liberation Organization's more moderate wing because while each advocates an independent Palestinian state, they also have said publicly that they would in return recognize Israel's right to exist. Each has met with Israeli leaders, either publicly or in private.

"I'm sure that radicals on both sides will be saying that moderate Palestinians are a very small and endangered species," said a western diplomat who knows all three men. "As for the moderates themselves, they'll be more careful and maybe keep a lower profile in the press."

Nusseibeh, 38, gained attention in recent months for advocating that Palestinians recognize the permanence of the Jewish state and of Israel's occupation of the West Bank and consider demanding that Israel annex the area and grant them full citizenship. Such a move would force Israelis to decide whether they want a binational state of Jews and Arabs or whether they would rather accede to an independent Palestinian homeland.

His idea was denounced by many Palestinians, yet Nusseibeh said he had never been personally threatened, something that he and others cited as a sign of growing political maturity on the part of Palestinians in the West Bank.

"Ten years ago, Sari would have gotten a bullet in his head for saying those things," said a Palestinian journalist here.

Palestinian radicals were more angered over Nusseibeh's willingness to meet publicly with such Israeli leaders as Foreign Minister Shimon Peres. Nusseibeh was expelled from the Bir Zeit employes' union, which he had helped found, after meeting with Peres last year.

Last week Nusseibeh confirmed to reporters that he, Husseini and Palestinian editor Salah Zuhaika had met several times in recent months with Moshe Amirav, a Central Committee member of Prime Minister Yithak Shamir's rightist Likud bloc. Nusseibeh said the meetings apparently had the tacit blessing of Shamir.

But Shamir's office denounced the meetings and has strongly denied that the prime minister knew of them.