By Anushka Asthana, Political Correspondent
The RAF has launched a probe after photographs surfaced appearing to show a serviceman posing with a dead Taliban fighter.
The pictures were apparently taken in the wake of an attack by 15 insurgents on Camp Bastion, the main British base in Afghanistan, in September 2012.
The insurgents breached the perimeter of the base, triggering a battle involving a British RAF regiment and US marines.
Two of the marines and 14 Taliban fighters were killed in the firefight, and UK troops were also injured.
The two photographs appear to show at least one member of the RAF giving a thumbs-up sign as he kneels next to the body of a dead insurgent.
The photos were taken after an attack on Camp Bastion in 2012 It is unclear if it is the same serviceman in both of the photographs.
Sky News has learned that the individual or individuals belong to 51 Squadron.
An RAF source said he was making "no excuses" for the behaviour but said it was important to consider the context.
"This was a long, extensive firefight against a well-drilled, well-armed enemy who was trying to kill them," the source said.
He spoke of the "heat of conflict", the "relief of victory" and the "unusual adrenaline fuelled situation" in which "foolish" things happened.
Camp Bastion is the main British base in Afghanistan The investigation will focus on whether the airman broke the rules by "mistreating" the enemy.
They may also be reprimanded for simply having and using photographic equipment.
Another photograph shows a burned-out plane in a hangar - six US Harrier jets were destroyed in the attack.
The images first appeared on the website Live Leak.
An RAF spokesman said: "Inappropriate actions will not be tolerated in the armed forces.
"The RAF is treating this incident extremely seriously and has launched a military police investigation.
"As this incident is subject to an ongoing investigation it would be inappropriate to comment further at this time."
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