The Turkey-based Association of Detainees and the Missing in Sednaya Prison (ADMSP) said in a 2022 report that the prison “effectively became a death camp” after the start of the conflict.

It estimated that more than 30,000 detainees had either been executed or died as a result of torture, lack of medical care or starvation at the facility between 2011 and 2018.

It also cited released inmates as saying that at least another 500 detainees had been executed between 2018 and 2021.

ADMSP also described how “salt chambers” were constructed to serve as primitive mortuaries to store bodies before they were transferred to Tishreen Military Hospital in Damascus for registration and burial in graves on military land. The detainees’ families were never given their bodies, it said.

Amnesty International used the phrase “human slaughterhouse” to describe Saydnaya and alleged that the executions had been authorised at the highest levels of the Assad government, and that such practices amounted to war crimes and crimes against humanity.

The Assad government dismissed Amnesty’s claims as “baseless” and “devoid of truth”, insisting that all executions in Syria followed due process.