Britain's ministry of defence is investigating the death of an Afghan girl who died after being hit by a box of leaflets dropped by the Royal Air Force.
The information leaflets were dropped in boxes from an RAF Hercules aircraft over a rural area of Helmand province in southern Afghanistan on 23 June.
The box failed to break apart in mid-air and landed on top of the girl who died later in hospital.
The MoD said on Wednesday the girl's death is a matter of "deep regret", and a full investigation is under way.
US and British forces regularly drop leaflets with information on election campaigns and military action in an area.
Officials said it was not known what type of leaflet was involved.
"Sadly one of the boxes failed to fully open and on landing caused serious injuries to an Afghan child," a Royal Air Force spokesman said in a statement.
"The child was treated at the local medical facility in Kandahar where despite the best efforts of staff she died as a result of her injuries."
The MoD said it was believed to be the first time a civilian had been killed by such an airdrop.
Britain has about 9,000 troops in Afghanistan, mainly in Helmand. Some 40 British soldiers have been killed in Afghanistan in the past two months and 218 have died there since the US-led invasion in 2001, a greater death toll than during the Iraq war.