New York - Human Rights Watch on Wednesday called on the Saudi government to release immediately and unconditionally Matrook al-Faleh, a leading defender of human rights and political scientist.

Al-Faleh was arrested on Monday at King Saud University in Riyadh, where he was teaching political science.

Human Rights Watch said he was arrested two days after publicly criticizing conditions in a prison where two Saudi human rights activists are serving jail terms.

"Saudi Arabia's arrest of Matrook al-Faleh confirms that human rights advocacy in that country remains a risky business," said Joe Stork, of Human Rights Watch's Middle East division. "By suppressing peaceful dissent, Saudi Arabia only stands to gain further notoriety as an abuser of human rights."

Human Rights Watch had tried to obtain information about al-Faleh with the country's interior ministry, but it received no response. (dpa)