Farhan, 32, who used his blog to criticize corruption and call for political reform, was detained "for violating rules not related to state security," according to the spokesman, Maj. Gen. Mansour al-Turki, responding to repeated requests for comment with a brief cellphone text message.
Farhan's Dec. 10 arrest was reported last week on the Internet and has been condemned by bloggers in Egypt, Tunisia, Morocco and Bahrain. The Saudi news media have not yet reported the arrest, but more than 200 bloggers in the kingdom have criticized Farhan's detention, and a group of supporters have set up a Free Fouad Web site.
Farhan, who was educated in the United States and owns a computer programming company, was arrested at his office in Jiddah and then brought home, where his laptop was confiscated, said his wife, who spoke on condition that her name not be published to protect her privacy. "They arrested him because of his blog. I haven't seen him since. We don't know where he is," she said.
Saudi Arabia, an absolute monarchy that restricts press and speech freedoms, does not allow political parties, civil rights groups or public gatherings. But since King Abdullah took the throne in 2005, official tolerance of criticism and debate has grown.
Even so, Farhan told The Washington Post and others in early December that an Interior Ministry official had warned him that he would be detained because of his online support for a group of men arrested in February and held without charge or trial.
At the time of their arrest, the government accused the Jiddah-based group, made up of a former judge, academics and businessmen, of supporting terrorism. The men's attorney, Bassim Alim, had said they were arrested for their political activism and their plans to form a civil rights group.
Farhan's friends have maintained his blog during his detention and posted on it an e-mail he had written to a friend shortly before his arrest.
Farhan wrote that he was told he would be released if he signed an apology for his activism. "I'm not sure if I'm ready to do that. An apology for what? Apologizing because I said the government lied when they accused those guys of supporting terrorism?"
In October, Farhan visited one of the jailed men and wrote about it on his blog, http://www. alfarhan.org.