Khaleej Times runs this AFP story. No further details are available at the moment.

UPDATE: Saudi Jeans has more information, including his belief that the arrest was consequent to Al-Faleh’s statements about prison conditions in the KSA. More here.

UPDATE: The Washington Post’s correspondent in Saudi Arabia offers her take on the story: Saudi Critic Jailed After Decrying Justice System

Leading Saudi reformist arrested: wife

DUBAI – Leading Saudi reformist Matruk al-Faleh, who once served almost a year and a half in jail for demanding a constitutional monarchy, has been arrested, his wife told AFP on Tuesday.

Jamila al-Ukalaa said she was informed by the security services in a telephone call at midnight on Monday that her husband had been arrested in Riyadh.

“I was told he is in the custody of the security services. They did not give me any reason,” she said by telephone.

Ukalaa said she had gone to the university where Faleh teaches to look for him on Monday after he failed to come home and found only his car in the parking lot.

Faleh was among three prominent Saudi reformists who spent 17 months in jail for demanding a constitutional monarchy before being pardoned by King Abdullah in August 2005.

Mufleh al-Kahtani, vice president of the National Society for Human Rights, told AFP that the the Saudi rights watchdog was “following up the case,” but he did not know the reason for Faleh’s arrest.