As many as 13,000 people were hanged in five years at a notorious Syrian prison near Damascus, Amnesty International has said, accusing the government of a "policy of extermination".
Titled "Human Slaughterhouse: Mass hanging and extermination at Saydnaya prison," Amnesty's damning report, released on Tuesday, is based on interviews with 84 witnesses, including guards, detainees, and judges.
It found that at least once a week between 2011 and 2015, groups of up to 50 people were taken out of their prison cells for arbitrary trials, beaten, then hanged "in the middle of the night and in total secrecy.
"Throughout this process, they remain blindfolded. They do not know when or how they will die until the noose was placed around their necks," the report said.
Most of the victims were civilians believed to be opposed to the government of President Bashar al-Assad.