The US has accused the Syrian government of carrying out the mass killings of thousands of prisoners at a military prison before burning their bodies in a huge crematorium.

Washington said on Monday (15 May) that Syrian President Bashar al-Assad's government "has sunk to a new level of depravity" by burning scores of bodies in a large crematorium outside Damascus.

Amnesty International published a report in February 2017 stating that the Saydnaya prison, about 45 minutes from the capital, was being used to hang and torture detainees for the last four years, with around 13,000 detainees being killed.

Now the US has officially accused the Syrian regime for the first time of killing prisoners at the jail.

"We now believe that the Syrian regime has installed a crematorium in the Sednaya prison complex which could dispose of detainees' remains with little evidence," said Stuart Jones, acting assistant secretary of state for Near Eastern Affairs, according to Reuters.

The Trump administration released satellite photographs showing a building in the prison complex that they believe was modified to contain a crematorium.

 Saydnaya military prison
Saydnaya military prison, around 45 miles outside Damascus, has been the scene of mass executions claims Washington. Amnesty International

Although the images, taken in 2013 and 2015, do not definitely prove the building is a crematorium, they show construction within the military site that would be consistent with such use.

Jones added that Assad's government "has sunk to a new level of depravity" with the support of both Russia and Iran, who have been supporting his regime fighting rebels and Islamist insurgents.

Amnesty International claimed that around 50 detainees a day were killed, with their bodies being burned in the crematorium, just yards away, from 2011.

The report said prisoners were hanged in secret at the prison, once or twice a week in the middle of the night, after trials that lasted just minutes, according to former detainees.

The reports contents were denied by the Syrian Justice Ministry, via state run news agency Sana, as "totally untrue".

Amnesty said of the Assad regime itself: "It is inconceivable that these large-scale and systematic practices have not been authorised at the highest levels of the Syrian government."