A marine who died in Afghanistan may have been killed in a friendly fire incident involving an American aircraft, the BBC has learned.
Jonathan Wigley died as a result of attempts to dislodge Taleban forces
British forces have now launched an inquiry into Jonathan Wigley's death in heavy fighting in Helmand province.
It seems likely that he was killed by "friendly fire" during an intense battle, said BBC correspondent Alastair Leithhead, reporting from Kabul.
The Ministry of Defence could not give any more details ahead of the probe.
The 21-year-old marine, from Zulu Company 45 Commando Royal Marines, had been taking part in a planned operation to drive Taleban forces out of Garmser town centre, explained the BBC correspondent.
But the Taleban counter attack was "more intense than anticipated and the marines were only able to pull out after a 10-hour fire-fight".
They were supported at close quarters from the air by British helicopters and American A10 and F18 aircraft, he added.
Alastair Leithhead said it is thought one of those planes was responsible for marine Wigley's death, but the MoD could not give any further information ahead of the inquiry.
The investigation is expected to take several months to complete.
British forces are still engaged in numerous daily attacks across Helmand province.
Marine Wigley, the 19th serviceman to die in combat this year in the province, was wounded and airlifted to the UK military hospital at Camp Bastion, but died of his injuries on Wednesday.
Another serviceman was also injured in the battle.
The "outstanding" serviceman, from Melton Mowbray in Leicestershire, grew up in Grantham, Lincolnshire.
He joined the Royal Marines aged 17, and was based at RM Condor in Arbroath, Angus.