Human rights groups say Saudi authorities have released a 70-year-old activist, but that nine others remain detained following a sweep that targeted women's rights activists.

Amnesty International and two Saudi human rights groups operating abroad said on Thursday Aisha al-Mana was released, but that the conditions of her release remain unknown. Activists had said al-Mana previously suffered a stroke and were concerned for her health while under arrest.

Al-Mana took part in the first protest in 1990 against the kingdom's ban on women driving.

People familiar with the arrests say those still detained — six women and three men — have been interrogated without access to lawyers and were allowed just one phone call to relatives. One of the women has been held entirely incommunicado since her arrest last week.