Armoured vehicles come and go from the airport in Jalalabad, one of the biggest cities in eastern Afghanistan. Locals don't know much about who travels in them, but they do know one thing: they are to be feared.

Quartered behind the airport's razor wire is a secretive CIA-backed Afghan special forces unit that has been accused of human rights atrocities.

The CIA backs numerous forces in Afghanistan, but finding out more information about them is extremely hard, both because of the fear the militias inspire in the local population and because of the CIA's lack of transparency.

But local outrage at abuses by CIA-backed forces in Afghanistan is gradually dragging these shadowy forces into the spotlight. Last month the New York Times published a major expose on these groups and the civilian casualties attributed to them.

The New York Times documented abuses carried out by these Afghan special forces units during ground raids: in one particularly brutal incident two brothers were hooded and executed in the corner of a room which was then detonated. But even more destruction is possible if air strikes can be called in by such groups on their targets. An investigation by the Bureau has uncovered instances where this has happened.

We focused on a branch of special forces working under the Afghan intelligence agency (known as the NDS) It operates from the Jalalabad air-base in Nangarhar province and is backed by the CIA. Known by many as the “02” unit, its on-the-ground activities are supported by air strikes carried out by both US and Afghan forces, senior Afghan intelligence officials told the Bureau.