International rights groups have questioned the regime's reform agenda after the activists were identified and called traitors in the media. All those arrested had called for an end to the ban on women driving cars.
Amnesty International and Human Rights Watch called on Saudi authorities to release seven detainees arrested in Saudi Arabia for "attempting to undermine the security and stability of the kingdom... and to erode national unity," according to a report by Saudi Arabia's state security service cited by Reuters news agency.
"Saudi Arabia cannot continue to publicly proclaim support for women's rights and other reforms while targeting women human rights defenders and activists for peacefully exercising their rights to freedom of expression, association and assembly," said Samah Hadid, Amnesty's Middle East Director of Campaigns.
The detainees have been accused of making "suspicious contact with foreign parties," providing financial support to "hostile elements abroad" and recruiting government workers, according to the Saudi authorities.
The men and women arrested have all campaigned for women to be allowed to drive after a ban lasting decades. The decision to lift the ban, due to come into force on June 24, had been seen as part of a progressive trend under Crown Prince Mohammed bin Salman.
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Amnesty criticized media coverage of the case as a "chilling smear campaign" designed to intimidate and discredit the activists and an "extremely worrying development for women human rights' defenders" in Saudi Arabia.
Human Rights Watch described the crown prince's reform campaign as "a frenzy of fear for genuine Saudi reformers who dare to advocate publicly for human rights or women's empowerment."
"The message is clear that anyone expressing skepticism about the crown prince's rights agenda faces time in jail," said Sarah Leah Whitson, Middle East director at Human Rights Watch.
There are suggestions that authorities want to avoid appearing to reward activism, which is forbidden under the Saudi monarchy. "It appears the only 'crime' these activists committed was wanting women to drive before Mohammed bin Salman did," Leah Whitson added.
The activists had also called for an end to other forms of discrimination in Saudi Arabia, such as the guardianship laws that give male relatives a final say on whether a woman can travel abroad, obtain a passport or marry.
kw/jm (AP, Reuters)