There was little that could be done by the time Dr Osama Abu El Ezz arrived at the scene of the nerve agent attack on his family’s village of Khan Sheikhoun in Idlib, northwest Syria, in April last year.

He remembers the vacant eyes, the frothing mouths and the chests of the victims heaving as they struggled for their last breath.

But most of all he remembers the feeling of anger that followed, when he and his colleagues were accused by detractors of framing President Bashar al-Assad’s forces.

“It was like the videos and testimonies were not enough,” Dr Abu Ezz, a general surgeon at Atareb hospital, told the Telegraph. “It was very upsetting that anyone could think we would do this to our own…