BBC News with David Legge

The commander of United States and Nato forces in Afghanistan, General David Petraeus, has ordered an investigation into the death of a kidnapped British aid worker killed during a rescue attempt on Friday. His announcement comes after the US military revealed that the aid worker Linda Norgrove may have been killed by a grenade thrown by American troops trying to rescue her. From Kabul, Nicholas Witchell has this report.

For 48 hours over the weekend, officials here had spoken about an explosion initiated by one of the extremists, possibly from a suicide bomb vest. Quite why it took the Americans so long to verify the accuracy of the picture they were giving isn't clear, but this morning they suddenly disclosed that surveillance footage together with discussions with members of the team meant that they could not now conclusively determine the cause of Ms Norgrove's death. There will now be a joint investigation by the American and British military, which is likely to take several days.