A British soldier has been killed in the Afghan capital, Kabul, in the city's second suicide bomb in two days.
Troops seal off the site of the suspected suicide bombing
The blast injured four other UK soldiers, two of them seriously, and an Afghan interpreter. Names are not being released until families have been told.
The British army confirmed it was a suicide attack shortly after the Taleban said they carried it out.
A suicide bombing on Tuesday killed a Canadian member of the international peacekeeping force in Kabul.
That, too, was claimed by the ousted Taleban, who have recently issued warnings of a new wave of attacks against peacekeepers and other foreigners in Afghanistan.
About 350 British troops are in Kabul as part of the Nato-led International Security Assistance Force (Isaf).
The commander of British troops in the city said the attack, using at least 200 pounds of explosives, looked carefully planned.
Colonel Mike Griffiths said there had been a single suicide bomber, travelling in a taxi with Kabul number plates.
The British troops were in lightly protected Land Rovers, on a main road in the city's eastern suburbs.
As the lead driver overtook the taxi, it blew up.
The colonel said the blast had catapulted debris over a wide area.
Most of the casualties were in the lead Land Rover, but some in the second vehicle were lightly injured.
The BBC's Andrew North in Kabul saw rubble strewn across the tarmac.
Eyewitnesses nearby at the time of the explosion spoke of seeing human remains scattered around the blast site.
The Taleban's top spokesman told the BBC his movement had carried out the attack.
"No patriotic Afghan supports occupation of Afghanistan by foreign forces," Hamid Agha said.
An Isaf spokesman denied there had been a second explosion outside a German military facility on the other side of the city.
'Switch in tactics'
Kabul is one of the few places in Afghanistan considered secure enough for foreigners to operate, although there have been a number of attacks there.
The commander of Canadian peacekeepers in Afghanistan said Tuesday's bomb which killed one of his soldiers showed opponents were changing tactics.
December and January saw a huge security operation in Kabul when delegates from all over Afghanistan met at a grand council (loya jirga) to draw up a new constitution for the country.
Despite the security there were a number of explosions blamed on the Taleban during the meeting.