Rebel fighters told reporters they found around 40 bodies bearing signs of torture inside a hospital morgue near Damascus on Monday, stuffed into body bags with numbers and sometimes names written on them.

"I opened the door of the morgue with my own hands, it was a horrific sight: about 40 bodies were piled up showing signs of gruesome torture," Mohammed al-Hajj, a fighter with rebel factions from the country's south told reporters by telephone from Damascus.

There were dozens of photographs and video footage that Hajj said he took himself and showed corpses with evident signs of torture: eyes and teeth gouged out, blood splattered and bruising.