Amnesty International released a report that covered the uprising from its start, and up until 2015. During that time period, Amnesty says that groups of 20 to 50 people were hanged once or twice a week in the middle of the night at Saydnaya Prison.  Allegedly, these killings were authorized by senior officials, including deputies of President Bashar Assad.

“The horrors depicted in this report reveal a hidden, monstrous campaign, authorized at the highest levels of the Syrian government, aimed at crushing any form of dissent within the Syrian population,” said Lynn Maalouf, deputy director for research at Amnesty’s regional office in Beirut.

She told The Associated Press the detainees were only told they were sentenced to death “a few minutes before the noose is tied around their neck.” She added, “These executions take place after a sham trial that lasts over a minute or two minutes, but they are authorized by the highest levels of authority.”  She said these included the Grand Mufti, a top religious authority, and the defense minister. 

Amnesty based its findings on interviews with 31 former detainees and more than 50 officials, including prison guards and judges.

According to Amnesty, torture and abuse was’t limited to Saydnaya, a prison run by the military police. The group documented over 17,000 deaths from torture and abuse in detention facilities across Syria, in a report they released last year.

The Syrian security force’s severe crackdown on protests in 2011 led many opponents of the government to take up arms. The resulting civil war killed an estimated 400,000 people.

Syrian officials rarely comment on allegations of torture in the country’s prisons, but they do deny the accusations of mass killings.

Amnesty has called upon the Syrian government, demanding an end to extrajudicial killings and torture in Saydnaya, which is one of the country’s largest prisons. It also called on the Syrian government’s closest allies, Russia and Iran, to pressure it to end its “calculated campaign” against dissent.