In the week that the US military pledged a new effort to avoid civilian casualties in Afghanistan, Channel 4 News has video evidence of an attack that may have killed up to 140 civilians.

Airstrikes have long been a lethal coalition tactic, but the question of how targets are assessed refuses to go away.

Late yesterday around 70 people were killed across the border in the south Waziristan region of Pakistan, when a US drone struck mourners attending the funeral of a militant. It is not known if civilians were among the dead.

A previous attack in May saw up to 140 civilians die in Farah province in a US airstrike.

The United Nations estimates that in 2007 there were over 1,500 civilian deaths in Afghanistan. In 2008 there was a 40 per cent increase, with over 2,000 deaths recorded, although over half of these were due to the Taliban.



Our report by our diplomatic editor Jonathan Rugman contains some distressing images.