Media playback is unsupported on your device Media caption Extract from helmet camera recording of incident in Helmand, Afghanistan

A recording of a conversation between three Royal Marines as they allegedly murdered a captured Afghan insurgent has been released by a judge.

In the clip, recorded on one marine's helmet-mounted camera, a gunshot is heard, then groans from the insurgent.

The prosecution at the court martial says the shooting was in effect an execution.

The trio, Marines A, B and C, deny murdering the man while on duty in Helmand province in 2011.

Marine A is accused of shooting the man, while Marines B and C are said to have been "party to the killing".

Warning: the transcript of the exchange below contains strong language.

Judge Jeff Blackett, judge advocate general, had ruled that the video capturing the incident should not be released because it could be used as propaganda by terrorists.

But he ruled at the court martial in Bulford, Wiltshire, that the audio could be published as the panel retired to consider the case at after two weeks of evidence.

The six minutes and 24 seconds of footage shows the Royal Marine patrol waiting outside a field of tall crops, with an Apache helicopter audible overhead.

They can be heard swearing and complaining about their task of carrying out a "damage assessment" after the helicopter attack.

The court martial heard the insurgent had been shot at with 139 30mm anti-tank rounds but was still alive - albeit seriously injured - when discovered by the patrol.

Marines A and C are seen scouting out the field and locating the Afghan before calling the others over.

As Marine B walks towards them, the camera captures its first shot of the insurgent - lying on the ground, covered in blood. The patrol drags the man across the field and into a wooded area nearby.

The film shown to the court shows Marine A shooting the Afghan prisoner with a 9mm pistol at close range before saying: "There you are. Shuffle off this mortal coil... It's nothing you wouldn't do to us."

Prosecutors allege he then turned to his comrades and said: "Obviously this doesn't go anywhere, fellas. I just broke the Geneva Convention."

The transcript of the recording includes:

"Do you want him back in?"

"I want him back in here so I can see what I'm fucking doing."

[Movement]

"Err, anybody want to do first aid on this idiot?"

"No"

"Nope."

"Could put one in his head if you want? Take your pick."

[Laughter]

"Not in his head because that will be fucking obvious."

Marine A told the court martial that he believed the man was already dead when he fired the shot.

The court heard the incident occurred after a patrol base came under attack from small arms fire from two insurgents.

The case has been adjourned until Friday.