The Trump administration on Monday accused the Syrian government of installing a crematorium at a prison outside Syria's capital for the disposal of thousands of bodies of prisoners executed in mass killings.

A State Department official said that the U.S. believes Syrian President Bashar Assad is using the crematorium to cover up mass murders at the prison complex, Reuters reported.

"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," Stuart Jones said. "Credible sources have believed that many of the bodies have been disposed in mass graves."

ADVERTISEMENT

In light of the information about the mass killings, Jones said that Russia's calls for "de-escalation zones" in the country would be met with "skepticism."

"In light of the failures of the past ceasefire agreements, we have reason to be skeptical," he said. "The regime must stop all attacks on civilian and opposition forces."

A report by the international rights group Amnesty International found that between 25 and 50 executions are performed at the prison every week. The complex is located just 45 minutes outside Syria's capital of Damascus, the seat of the Assad government's power.

President Trump ordered airstrikes on a Syrian airfield last month after Assad used chemical weapons on civilians, including children.