--From CNN's Roba Alhenawi, Mohammed Jamjoom and Joe Sterling

(CNN) -- A Saudi Arabian political science professor who is an outspoken
human rights advocate was taken into custody this week by the country's secret
police, his wife confirmed to CNN on Friday.

Human Rights Watch -- which issued a report condemning the arrest and
urging the release of Matrook al-Faleh -- said the man was seized at King Saud
University in Riyadh "two days after he publicly criticized conditions in a
prison where two other Saudi human rights activists are serving jail terms."

Jamila al-Uqla, al-Faleh's wife, said her husband went to the university
on Monday but didn't return. She was informed later that day by police that he
was detained at the police's main detention facility.

Police asked her to call them back. The next day, she tried to ring them
again but no one could give her more details about where he was. Police did not
say why he was seized and she has not heard from him since.

"I keep calling the secret police, but they keep denying they're holding
him at their facility," she said, adding "I have called his cell phone but
there is no answer. He has not called even once."

Al-Uqla said she and al-Faleh, 54, are patriotic Saudis.

"My husband is transparent and doesn't hide anything. He says whatever he
sees. He has loyalty to his country and the interests of his country," she
said.

Joe Stork, deputy director at Human Rights Watch's Middle East division,
said the arrest shows "that human rights advocacy in that country remains a
risky business."

"By suppressing peaceful dissent, Saudi Arabia only stands to gain
further notoriety as an abuser of human rights," Stock said in the Human Rights
Watch report.

Phone calls to Saudi Arabia's Interior Ministry seeking comment were not
answered.

On Saturday, Human Rights Watch said al-Faleh sent an e-mail to human
rights activists and journalists about "visiting procedures" and "detention
conditions" at a Buraida General Prison, where his activist friends are being
held.

He called the visiting procedures laborious and compared the visiting
area to a "chicken coop."

"Al-Faleh's fellow activists, the brothers Abdullah al-Hamid and Isa
al-Hamid, are serving prison sentences at Buraida General Prison for expressing
support for a demonstration that took place in front of Buraida's secret police
prison by wives and relatives of long-term detainees held there without
charge," the group said.

He said the activists decried the prison's conditions as filthy and
crowded with poor health care, according to Human Rights Watch -- which said it
independently confirmed such conditions.

"It is outrageous that the Ministry of Interior arbitrarily arrests Dr.
al-Faleh rather than addressing the inhumane conditions he documented," Stork
said.

Al-Faleh, Abdullah al-Hamid and Ali al-Dumaini, who runs a Saudi
discussion site, were arrested in 2004 "for circulating a petition to
then-Crown Prince Abdullah calling for a constitution guaranteeing basic human
rights. A court sentenced the three to six, seven, and nine years in prison
respectively, but King Abdullah pardoned them in August 2005," Human Rights
Watch said.

Al-Faleh's recent statement had been "reproduced on menber-alhewar.info,"
al-Dumaini's Web site, Human Rights Watch said.

In contrast to Monday's detention, al-Uqla said police in 2004 allowed
her husband to call her just after his arrest.

In December, Saudi authorities arrested blogger Fouad al-Farhan "after he
called for the release of a group of detained peaceful reform activities." He
was released in April.