The Government has defended a failed rescue mission in Afghanistan during which a British hostage was murdered by her rebel captors.
Prime Minister David Cameron said it was "right to try" to secure the release of Linda Norgrove, a 36-year-old aid worker from Scotland.
General David Petraeus, the top Nato and US commander in Afghanistan, added that troops did "everything in their power" to save a woman colleagues described as an "inspiration".
Originally from Sutherland in the Scottish Highlands, Ms Norgrove was seized by militants in Kunar province on September 26. Three Afghan nationals also taken by the insurgents were later released, but Ms Norgrove continued to be held amid growing concern.
After a tip off revealed her whereabouts, US troops in the eastern province were sent in. During the fighting seven insurgents were shot dead, it is believed. But Ms Norgrove was killed by her captors before she could be secured and led to safety.
Authorities in the US and the UK stressed that insurgent captors alone were responsible for the death. "There is nothing at all to suggest that US fire was the cause," a Foreign Office spokesman said.
Foreign Secretary William Hague broke the news of the failed rescue bid. He said: "Responsibility for this tragic outcome rests squarely with the hostage takers. From the moment they took her, her life was under grave threat. Given who held her, and the danger she was in, we judged that Linda's best chance lay in attempting to rescue her."
In a statement, Mr Cameron added: "Decisions on operations to free hostages are always difficult. But where a British life is in such danger, and where we and our allies can act, I believe it is right to try."
A former United Nations employee, Ms Norgrove was working for the firm Development Alternatives Inc (DAI) at the time of her kidnap. Based in Jalalabad, she supervised reconstruction programmes in the eastern region of Afghanistan funded by the US government.
Tributes in Scotland were led by first minister Alex Salmond. He said the news was "extremely sad and upsetting", adding: "Ms Norgrove was a dedicated aid worker who was doing everything she could to help people in Afghanistan - hopefully that legacy of service in a humanitarian cause can be of some comfort to her loved ones in their time of grief."