Qatar commissioning the report and its release just before the Geneva talks - should not obscure the reality of the evidence produced.

Analysis

Jim MuirBBC News, Beirut

There have been many reports and much evidence collected by human rights groups and international investigators alleging systematic torture and killings in Syrian government detention centres.

But the latest report carries such allegations into a new dimension. The figure of 11,000 victims documented in the 55,000 photographs is clearly just the tip of the iceberg, representing the numbers in one location only, and with a large number of the images (27,000) taken by one official photographer.

This man, codenamed "Caesar", was later smuggled out of Syria and questioned by three top war crimes prosecutors for several days at an undisclosed location. They concluded that his testimony was "not only credible, but most compelling".

Issues of political motivation - the commissioning of the report by Qatar, and its release just before the Geneva talks - should not obscure the reality of the evidence produced.

• Graphic images of abuse