A British SAS soldier who died fighting Islamic State in Syria was killed by friendly fire and not in a roadside bomb, as was previously believed.
Sergeant Matt Tonroe died last year alongside US commando Master Sergeant Jonathan J Dunbar while on a joint operation with American special forces.
The Pentagon blamed their deaths on an improvised explosive device (IED) in a statement released days after the incident in March 2018.
But an investigation into the blast in Manbij, northern Syria, has concluded Sgt Tonroe was killed by an explosive carried by a colleague.
Investigators could not rule out the possibility that a grenade carried by another coalition soldier killed both men, according to The Morning Star newspaper.
A Ministry of Defence spokesman said: "Sergeant Matt Tonroe died from blast injuries caused by an explosion during a military operation.
"It was initially believed that Sgt Tonroe was killed by enemy action, however subsequent investigation concluded that Sgt Tonroe was killed by the accidental detonation of explosives carried by coalition forces.
"Our thoughts continue to be with Sgt Tonroe's family and friends."
Sgt Tonroe was the only British soldier killed in active duty during operations against IS.