Saudi Arabia quietly and without explanation has released from prison a prominent Islamic dissident who was jailed without charges for more than eight years after he criticized the government.

Said Zuair, whose cause was championed by both Amnesty International and Osama bin Laden, spent his first day of freedom receiving hundreds of visitors. Among them were conservative clerics who have opposed the policies of the ruling monarchy, his son said.

No official explanation was given for the release of Zuair, a well-known cleric and a dean at Imam Mohammed bin Saud University. He was arrested in 1995 after signing a petition calling for political reform, an end to economic corruption and a stronger Saudi army that would eliminate the need for U.S. troops to be in Saudi Arabia.

His son, Abdullah Zuair, said the release could be an attempt to quiet public outrage over the war in Iraq.

But Zuair's lawyer, Amjad E. Salfiti, said in a telephone interview from London that it was more likely the result of a suit filed in Britain two weeks ago asking the attorney general there to bring criminal charges against the Saudi interior minister, Prince Nayef, alleging torture and illegal detention.

Human rights activists had called Zuair Saudi Arabia's longest-serving political prisoner.

Shortly before the one-year anniversary of the Sept. 11, 2001, attacks, the al-Jazeera television network aired a videotape of bin Laden calling for the release of several jailed Islamic sheiks and clerics, Zuair among them.