Saudi authorities have detained a columnist who supported ending his country's ban on women driving, activists have said.
The activists, who wished to remain anonymous for fear of retribution, said Tariq al-Mubarak was called by investigators in the capital Riyadh concerning a stolen car over the weekend.
When he arrived at the Interior Ministry's Criminal Investigation Department on Sunday, he was interrogated instead about his role in a campaign launched by reformers seeking the right of women to drive in the kingdom.
When his friends were informed they could pick him up at the investigator's office, they too were detained for several hours and questioned over the campaign's activities, activists said.
Human Rights Watch and activists who know al-Mubarak say he remains in detention with no access to a lawyer.
The New York-based organisation called for al-Mubarak's immediate release and on authorities "to stop harassing and trying to intimidate activists and women who defied the driving ban".
'Extremists intimidating activists'
In a column published in the pan-Arab daily Asharq al-Awsat the day of his arrest, al-Mubarak said religious extremists are intimidating people from exercising their rights.
He said the courts in Saudi Arabia do not have sufficient provisions to deter those who threaten and terrorise others from exercising their freedoms because "rights and freedoms ... are not instilled in our culture, nor our interpretation of religion".
Al-Mubarak, who also works as a schoolteacher, was among a core group of active young Saudis calling for women's right to drive.
About 60 women claimed they got behind the wheel on Saturday to oppose the ban. The campaign sparked protest by the kingdom's ultraconservative religious establishment.
The activists behind the October 26 driving campaign say their efforts are ongoing and that they continue to receive videos by women filming themselves flouting the driving ban.
At least two women have been fined recently by police for driving, the activists said. Samia El-Moslimany said she was given a nearly $135 fine for driving in the kingdom.
On Tuesday, about 150 religious scholars and clerics staged a rare protest outside Saudi king's palace against the women's driving movement.
Some of the senior religious leaders who protested outside the palace in the Red Sea port of Jeddah said the United States was behind a campaign.