A young Afghan girl suffered fatal injuries after a box of public information leaflets, dropped from an RAF transport aircraft over Helmand province, landed on top of her.

The accident, which the Ministry of Defence said yesterday was “highly regrettable”, is being investigated.

The incident has taken some time to emerge. The leaflet drop occurred on June 23. The crew of an RAF C130 Hercules had been flying over rural parts of the province to try to reach local people with a leaflet campaign.

The boxes of leaflets are supposed to open up in mid-air, scattering the literature over a wide area. “But on this occasion one of the boxes failed to open, and the young girl was hit,” an official said. Defence sources said it was unfortunate that the injured girl was taken to a local hospital in Kandahar, neighbouring Helmand province, where she died after being given emergency treatment.

“Normally, if a civilian is injured, for example, in crossfire, British soldiers will take him or her to the British field hospital at Camp Bastion where the best possible medical treatment is provided. In this case, we didn’t know about the girl until someone came forward later, after she had died, to tell us what happened,” the sources said.

The girl is one of a long line of innocent victims of the war, with some 1,500 civilians killed by violence in Afghanistan so far this year — 68 per cent were caused by insurgent attacks and 23 per cent by Afghan or Nato troops. The reasons for the rest have not been specified.

MoD officials said that an investigation was examining why the box failed to open. But steps had already been taken to improve safeguards to prevent similar incidents. “If her family request compensation, we will obviously give it consideration,” an official said.

An RAF spokesman said: “In a tragic incident on June 23, an airdrop of public information leaflets took place over a rural area in Helmand province. Sadly, one of the boxes failed to fully open and on landing caused serious injuries to an Afghan child. 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.”

MoD officials said that it was not known what type of leaflet was involved. They can range from basic warnings about improvised explosive devices to “mine awareness” guidance.

With the presidential election approaching on August 20, they may have contained information about where polling stations were going to be located, the officials said.

Some of the leaflet drops over Helmand involve black propaganda campaigns aimed at the Taleban. These are part of psychological warfare missions. But MoD officials said that they believed that the airdrop that led to the death of the girl had been a mission distributing basic public information guidance.

The MoD said that the airdrops were part of mass communication programmes and took place regularly. In the lead-up to the August election, several were occurring every week.

The boxes of leaflets weigh 30-40lb (14-18kg), but they are supposed to break open before landing specifically to avoid the risk of hurting civilians.

Death by airdrop has been recorded in previous campaigns when the RAF has distributed supplies to troops or humanitarian aid to civilians from the back of Hercules aircraft. But past incidents have involved large pallets of stores that have gone astray.

This is believed to be the first time that a civilian has been killed by a box of public information leaflets.