Amnesty International says Syrian authorities killed at least 13,000 people in mass hangings at a prison north of Damascus known to detainees as the “slaughterhouse.” The group released a report covering the period from the start of the 2011 uprising until 2015, during which Amnesty says groups of 20 to 50 people were hanged at Saydnaya Prison, once or twice a week, in killings authorized by senior officials, including deputies of President Bashar Assad. The report, issued on Tuesday, said that 20-50 people were hanged each week, sometimes twice a week, at the Saydnaya prison in what the organization called a “calculated campaign of extrajudicial execution.”

The report covers the period from the start of the March 2011 uprising to December 2015, when Amnesty says between 5,000 and 13,000 people were hanged. However, UN human rights experts said a year ago that witness accounts and documentary evidence strongly suggested that tens of thousands of people were being detained and that "deaths on a massive scale" were occurring in custody. Last August, Amnesty reported that an estimated 17,723 people had died in custody as a result of torture and the deprivation of food, water and medical care between March 2011 - when the uprising against President Assad began - and December 2015. "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," Lynn Maalouf, the deputy director for research at Amnesty's Beirut office, said in a statement announcing the report. There was no immediate comment from the Syrian government on Tuesday, and Amnesty said Damascus didn’t respond to its own letter seeking comment. A former guard said it held “the detainees of the revolution,” and a former judge said they were seen as “posing a real risk to the regime.”

The chilling accounts in Tuesday’s report came from interviews with 31 former detainees and over 50 other officials and experts, including former guards and judges. According to the report, detainees were told on the day of the hangings that they would be transferred to a civilian prison then taken to a basement cell and beaten over the course of two or three hours. The Amnesty report prompted a strong reaction from United Nations Secretary-General Antonio Guterres, who, “was horrified about what was in the report,” according to U.N. spokesman Stephane Dujarric.
A report by Amnesty International states that between 5,000 and 13,000 people, most of them civilians, were hanged at the military-run Sednaya Prison near Damascus between September 2011 and December 2015.