Footage emerging from the liberation of Bashar al-Assad’s most notorious prisons has revealed that the Syrian dictator used underground cells and body-crushing iron presses to detain and torture thousands of civilians.

Syrian rescue teams were still trying desperately to reach prisoners trapped in the underground labyrinth of jails deep inside the city of Sednaya on Monday.

Fleeting video clips taken by the first civilians and rebels to arrive at the prison – known locally as “the human slaughterhouse” – begin to show the horrors of the Assad regime’s interrogation and detention, where mass hangings, torture and sexual abuse are said to have taken place.

One clip shows a large iron press that is believed to have been used to break bones and execute prisoners, while endless red rope used for unknown torture methods lies discarded on the floor.