A young Afghan girl died after a box of public information leaflets, dropped by a British Royal Air Force plane over Afghanistan, landed on her, a newspaper said.

Britain's Ministry of Defence said it was investigating the accident which it described as "highly regrettable," The Times said.

The drop occurred over a rural area of Afghanistan's southern Helmand province on June 23 as part of an information campaign, the newspaper said.

"Sadly one of the boxes failed to fully open and on landing caused serious injuries to an Afghan child," an RAF spokesman said.

"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."

Officials said it was not known what type of leaflet was being dropped.

The accident comes amid anger in Afghanistan over civilian casualties in the conflict between foreign and Afghan forces and an increasingly bloody Taliban insurgency to secure the war-torn country.

- AFP