US president Barack Obama has offered his condolences for the death of British aid worker Linda Norgrove who died during a rescue attempt by US special forces in Afghanistan.
Mr Obama spoke last night by telephone with British prime minister David Cameron following the disclosure that she may not have been killed by her Afghan kidnappers as was originally claimed.
US central command yesterday launched an investigation into what happened, with members of the UK armed forces being invited to contribute.
"The president offered his condolences for the death of Linda Norgrove," a British government spokesman said. "They agreed that the decision to launch the rescue operation had been right, given the grave danger to Linda's life, and that US forces had shown great courage.
"The prime minister and the president agreed that it was now essential to get to the bottom of what had happened in the course of the rescue operation.
"They looked forward to close co-operation between the UK and US authorities on the investigation and agreed to stay in close touch as it moved forward."
US officials initially said that Ms Norgrove (36) died after her captors detonated a bomb vest as American troops attempted to free her on Friday night.
But General David Petraeus, the American commander of the Nato-led Isaf force in Afghanistan, told Mr Cameron yesterday that a second viewing of video recordings of the incident suggested she might have been the victim of "friendly fire".
In a statement, the US military said that a review of surveillance footage and interviews with members of the rescue team "do not conclusively determine the cause of her death".
Describing Ms Norgrove's death as "a tragedy", Mr Cameron has promised to do "everything I possibly can" to give her family certainty about how she died.
He said that the initial reports of how she died were "deeply regrettable" but were made in good faith on the basis of the information available.
Originally from Sutherland in the Scottish Highlands, Ms Norgrove was working for the US firm Development Alternatives Inc (DAI) in the east of Afghanistan when she was seized by militants in Kunar province on September 26th.
Gen Petraeus, who will visit London for scheduled talks with Mr Cameron on Thursday, said it was "our solemn responsibility to understand the circumstances which led to her death".
He added: "We will provide every measure of support to the investigation and will work closely with the British government to fully resolve this matter."
PA