A British SAS soldier who died in Syria was killed by the accidental detonation of an explosive carried by a colleague not by an enemy attack as previously believed.

Sergeant Matt Tonroe, an SAS sniper from Manchester became the first British soldier to be killed while fighting the Islamic State of Iraq and the Levant (Isil) in an operation in Syria last March.

He died alongside US commando Master Sergeant Jonathan J Dunbar while on a joint operation with American special forces.

The Pentagon initially attributed their deaths to the detonation of an improvised explosive device in Manbij, northern Syria but an investigation has now determined that Sgt Tonroe was killed accidentally.

"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,” A Ministry of Defence spokesman said.

Adding: "Our thoughts continue to be with Sgt Tonroe's family and friends."

The sniper was working as part of a global coalition force against Isil, supporting local groups fighting Islamic militants in Syria.

According to reports Sgt Tonroe was on a secret mission to capture or kill high-value personnel from Isil when he died. Five other people were injured in the blast. It is not known if the target of the mission was captured or killed.