The Taliban has claimed responsibility for the killing of five British soldiers by a rogue Afghan policeman.
The servicemen, three from the Grenadier Guards and two from the Royal Military Police, died when the officer turned his gun on them at a checkpoint in Nad-e-Ali in Helmand Province on Tuesday.
Another six British soldiers and two Afghan policemen were wounded in the shooting, which sent shockwaves through the coalition mission in Afghanistan.
Prime Minister Gordon Brown told the House of Commons that the Taliban had claimed responsibility for the killings.
Top British, US and Afghan commanders expressed deep regret for the incident, and pledged that it would be fully investigated.
Brigadier General Mirwais Noorzai, deputy regional commander of police, said Afghan officials were committed to uncovering the truth about what happened.
He told a press conference in Helmand's provincial capital, Lashkar Gah: "I have imparted our sympathy and regret to the families of the soldiers killed."
The killings took the UK death toll in Afghanistan since the conflict began in 2001 to 229, and made 2009 the bloodiest year for the Armed Forces since the Falklands War.
General Stanley McChrystal, the commander of Nato forces in Afghanistan, said he had received assurances from Afghan interior minister Haneef Atmar that the incident would be "fully and transparently investigated".
"We will not let this event deter our resolve to building a partnership with the Afghan national security forces to provide for Afghanistan's future," he said.
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