The UN yesterday declared that it had found “clear and convincing evidence” that surface-to-surface rockets loaded with the chemical nerve agent sarin were used to carry out mass killings in eastern Damascus last month.

In the first independent assessment of the attacks carried out on August 21, a team of UN inspectors said the massacre “unequivocally” involved the use of chemical weapons to kill civilians on a “relatively large scale”.

The inspectors said the remnants of munitions able to “carry a chemical payload” and “found to contain sarin” had been discovered in eastern Damascus. The report was published hours after a fresh split between the US and Russia over whether the process to rid Syria of its chemical weapons should include the threat of force if the regime does not comply.