The US has outright accused the Syrian government of killing thousands of prisoners and burning all of their bodies in a secret, large-scale crematorium.
The State Department said some 50 detainees a day are being hanged at Saydnaya military prison, which is around 45 minutes from the city.
It added that the crematorium is being used to hide evidence of the shocking extent of the killings.
Newly declassified photographs appear to show what the State Department says is a building in the prison complex that has been modified to support the crematorium.
Stuart Jones, the top US diplomat for the Middle East who presented the photographs, said that Assad’s government ‘has sunk to a new level of depravity’ with the support of Russia and Iran.
He called on both countries to use their influence with Syria to establish a credible ceasefire, and begin political talks.
Tens of thousands of people have been detained at the prison over the course of the country’s six-year civil war.
Releasing the photographs, Jones said: ‘We believe that the building of a crematorium is an effort to cover up the extent of mass murders taking place in Saydnaya prison.’
The satellite images show what it said is a building in the prison complex that has been modified to support a large-scale crematorium.
Although the photos, taken over several years starting from 2013, do not definitively prove the building is a crematorium, they do show construction consistent with such use.
One photograph taken in January 2015 shows one area of the building’s roof cleared of snow due to melting.
Jones also said that the US has ‘reason to be sceptical’ about a deal to set up ‘de-escalation zones’ that was brokered by Russia during ceasefire talks in Astana, the capital of Kazakhstan, last week.