Former UK special forces personnel have accused colleagues of committing war crimes in Iraq and Afghanistan, including alleging that they executed civilians and a child.

Graphic accounts of routine executions of handcuffed prisoners and the killings of people in their sleep were handed to the BBC, which reported that weapons were planted during cover-ups.

Veterans who spoke to the BBC spoke of a “mob mentality” among some former colleagues who were described as “lawless” and exhibiting “serious psychopathic traits”.

“They handcuffed a young boy and shot him,” said one veteran of the SAS in Afghanistan. “He was clearly a child, not even close to fighting age.”