Discuss as:

Report alleges torture, mass killings by Syrian government

A Syrian military photographer has defected and turned over evidence of torture and mass killings by the Syrian government, according to a report by three former international war crimes prosecutors published Monday.

The report, which was disclosed by the British newspaper The Guardian and hasn't been confirmed by NBC News, purports to document files and photographs smuggled out of the country by a military police photographer code-named "Caesar."

The documents include photos of as many as 11,000 detainees believed to have died at the hands of the Syrian government.

Many of the corpses in the photos showed evidence of starvation and torture, said the former prosecutors, who concluded that the documents would "support findings of war crimes against the current Syrian regime."

The government of President Bashar Assad has denied committing war crimes in its battle against opposition forces seeking his overthrow. 

But the report said the photographs were "a strong pointer to the fact that the killings were systematic, ordered, and directed from above."

Watch World News videos on NBCNews.com

The report was prepared by Desmond de Silva and David Crane, both former chief U.N. war crimes prosecutors for Sierra Leone, and Geoffrey Nice, who prosecuted former Yugoslavian President Slobodan Milosevic at the International Criminal Tribunal.

They were commissioned to review the evidence by the government of Qatar, a major backer of the opposition forces, The Guardian said. It said the report would be made available to the U.N., governments and human rights groups.

If the report is substantiated, it could significantly weaken Syria's hand at international peace talks scheduled this week in Switzerland. 

An unexpected last-minute U.N. invitation for Iran to attend the conference threw the talks into doubt, with the Syrian opposition saying it would pull out unless the U.N. withdrew the offer — which it later did.