Saudi activists, including women, arrested in a government crackdown this year have faced sexual harassment and torture during interrogation, Amnesty International said.
Since May, the kingdom has held at least 10 women and seven men on vague national security allegations related to their human rights work.
Those arrested include Loujain al-Hathloul, Eman al Nafjan and Aziza al-Yousef, who campaigned for the right to drive before the decades-long ban was lifted in June.
The activists, held in Dhahban prison on the western Red Sea coast, faced repeated electrocution and flogging, leaving some of them unable to stand or walk, Amnesty said in a report on Tuesday, citing three separate testimonies.
At least one activist was made to hang from a ceiling and another woman was sexually harassed by interrogators wearing face masks, the UK-based rights group added.
Many of those arrested were accused of undermining security and aiding enemies of the state.
Some were subsequently released, but those still held include al-Yousef, a retired professor at Riyadh’s King Saud University, Amnesty said.
The group’s report comes as Saudi Arabia faces intense global criticism over the killing of insider-turned-critic Jamal Khashoggi in its Istanbul consulate on October 2, which tipped the kingdom into one of its worst crises.