JERUSALEM, JAN. 30 -- Sari Nusseibeh, a prominent West Bank Palestinian leader who was arrested by Israel Tuesday as an Iraqi spy and jailed for six months without trial, denied today that he had ever engaged "in any intelligence gathering on behalf of any government or organization."

He said he was "convinced" his detention "has nothing to do with Iraq, with missile attacks, with violations of any security provisions or any other matter other than my own political views on the need for peace and moderation."

Far-right-wing leaders in Prime Minister Yitzhak Shamir's coalition government long had demanded Nusseibeh's arrest, and some observers here saw it as one of several aggressive moves the government has made in recent days to capitalize on its improved political standing in Western capitals and to position itself for a postwar diplomatic struggle.

Authorities alleged that Nusseibeh, a philosopher who is one of the most prominent Palestinian moderates, was coordinating espionage for Iraq by channelling data on sites struck by Iraq's Scud missiles to sources outside Israel. But officials refused to provide evidence and said they would not air their case in court by putting Nusseibeh on trial.

Palestinian leaders and Israeli leftists dismissed the allegations as "ridiculous" and charged that the government was taking advantage of the war to destroy the moderate Arab leadership.

"This is a message to us Palestinian moderates," said Saeb Erakat, another West Bank leader. "The message is you can forget about negotiations after the war because we are going to make sure there is no one to talk to."

Galia Golan, of the Israeli movement Peace Now, said she and other Israeli leftists met with Nusseibeh before his arrest to complain about the Palestine Liberation Organization's backing of Iraq. She said Nusseibeh promised to issue a statement condemning Iraqi missile attacks on Israel and reaffirming his commitment to a negotiated settlement between Israelis and Palestinians.