The Syrian regime has installed a crematorium in a military prison in order to destroy the remains of thousands of murdered prisoners, the US alleged Monday (May 15th).

The US State Department released satellite images that it said backed up reports of mass killings at a Syrian jail, AFP reported.

"The US is on record, has stated many times, that we are appalled by the atrocities that have been carried out by the Syrian regime," said Stuart Jones, the top US diplomat for the Middle East.

One newly released image, a commercial satellite photograph dating back to January 2015, shows snow melting on the roof of a building attached to the Saydnaya military complex north of Damascus.

This, along with an earlier picture allegedly showing heavy-duty ventilation systems on the structure, appears to support earlier claims by rights groups that Saydnaya is an execution centre.

"Beginning in 2013, the Syrian regime modified a building within the Saydnaya complex to support what we believe is a crematorium" built in "an effort to cover up the extent of the mass murders taking place in Saydnaya", Jones said.

At Saydnaya, Syria holds up to 70 prisoners in cells that are meant for five, Jones said, adding that "according to multiple sources, the regime is responsible for killing as many as 50 detainees per day at Saydnaya".

He did not give an official estimate for the total number killed, but cited an Amnesty International report that between 5,000 and 11,000 had died in the prison between 2011 and 2015.

The Syrian regime on Tuesday denied the allegations as "totally unfounded".