The brother of jailed Saudi activist Loujain Alhathloul has detailed the abuse his sister has endured in a Saudi prison.
In a CNN opinion piece, Walid Alhathloul wrote that during a recent visit by his parents to see Loujain she told them she was regularly whipped, beaten, electrocuted and sexually harassed in a basement she called the "palace of terror."
Alhathloul was arrested in May 2018, along with 10 other women's rights activists in Saudi Arabia. Her family, Saudi activists and Human Rights Watch have alleged in recent months that she and other female detainees have been tortured and sexually harassed in prison.
They also say that a former top adviser of Crown Prince Mohammed bin Salman, Saud al-Qahtani, was present during at least one of the interrogation sessions.
Qahtani allegedly threatened to rape, kill and throw one of the detainees into the sewage system, according to Human Rights Watch and people familiar with the events.
Qahtani was also implicated in the Istanbul consulate murder of Saudi journalist Jamal Khashoggi by Turkey and Saudi Arabia.
The former royal court communications chief was removed from his post after Riyadh pinned the blame for the murder on him and a handful of other high-ranking officials.
"Whenever Loujain spoke about the torture sessions to my parents, her hands shook uncontrollably. I fear the pain will stay with her forever," Walid Alhathloul wrote in the piece.
"My own baby sister said she is being whipped, beaten, electrocuted and harassed on a frequent basis," he wrote. "She said that sometimes there are masked men who wake her up in the middle of the night to shout unimaginable threats."
Walid Alhathloul also said that one of the investigators tried to pressure his sister into marrying him, threatening her with rape.
Saudi authorities did not immediately respond to CNN's request for comment on Alhathloul's allegations.
In addition to Loujain Alhathloul, the detainees include prominent women's rights activists Aziza al-Yousef, Eman al-Nafjan, Nouf Abdelaziz, Samar Badawi and Hatoon al-Fassi.
Riyadh previously denied allegations of torture in a statement to CNN following an initial Human Rights Watch report alleging the abuse in November.