LONDON (Reuters) - A British hostage who died in Afghanistan on Friday during a U.S.-led rescue mission may have been accidentally killed by the troops trying to save her, British Prime Minister David Cameron said on Monday.

Linda Norgrove, 36, who worked for a U.S. aid group, had been abducted on September 26 along with three Afghan co-workers when they visited a project in a remote part of Kunar province, a lawless region bordering Pakistan.
Britain's Foreign Office had said on Saturday that Norgrove had been killed by her captors during a failed rescue attempt.
Cameron said General David Petraeus, the commander of U.S. and NATO forces in Afghanistan, had contacted his office to say a review of events had revealed evidence indicating that Norgrove may not have died at the hands of her captors.
""That evidence, and subsequent interviews with the personnel involved, suggests that Linda could have died as a result of a grenade detonated by the task force during the assault,"" Cameron told a news conference at his Downing Street office.
""However, this is not certain, and a full U.S.-UK investigation will now be launched,"" he said.
Cameron said he took full responsibility for authorizing the operation to rescue the aid worker. He said intelligence at the time suggested Norgrove was about to be passed ""up the terrorist chain of command,"" placing her in an even more dangerous situation, and hence it had been urgent to act.
Photo: British aid worker Linda Norgrove is seen in this undated handout photograph released in London on October 9, 2010. A British aid worker abducted by gunmen in Afghanistan last month was killed by her captors during a rescue attempt, Britain's foreign minister said on Saturday. Norgrove, 36, had been held hostage in eastern Afghanistan since Sept. 26 after being kidnapped with three of her Afghan colleagues in Kunar province, a rugged region bordering on Pakistan held by the Taliban.
Credit: Reuters/FCO/Handout