Five members of NATO's international support mission in Afghanistan were killed and five injured when a British military helicopter crashed in the capital, Kabul, officials said on Monday.

NATO's Resolute Support mission, which gave the casualty figures but did not identify the nationalities of the dead and injured, said the crash happened on Sunday afternoon at its headquarters in Kabul. It gave no other details.

Britain's Ministry of Defence (MoD) said on its website that two Royal Air Force personnel had been killed when a UK Puma Mk 2 helicopter crashed while landing at the base.

"The incident is currently under investigation but we can confirm that it was an accident and not the result of insurgent activity," said the MoD news release, which made no mention of any other NATO casualties.

NATO's combat mission in Afghanistan has ended but around 12,000 mostly U.S. troops remain in Afghanistan as part of Resolute Support, focused on training Afghan security forces.