Four Britons have been injured in southern Afghanistan after a suicide bomber rammed their armoured vehicle with a car packed with explosives.
The attack happened close to a US military base near Kandahar
The attack, on a British Embassy convoy, happened on a main road about a kilometre from a US military base, near the city of Kandahar.
Two security guards were badly injured, and two others hurt less seriously.
The Foreign Office said none of the four, who work for the ArmorGroup, were in a life-threatening condition.
Kandahar governor Assadullah Khalid told Reuters the four Britons were on an official visit to help the local government with customs regulations.
He accused al-Qaeda and the Taleban of carrying out the attack.
An ArmorGroup spokesman Nick Melson said the families of the four employees had been informed and the company would providing support at this "difficult time."
"Anyone who works for ArmorGroup comes with a great deal of prior experience - many have served in either the armed forces or the police, " he said.
ArmorGroup provides security services in the world's trouble zones including Afghanistan and Iraq.
Reuters news agency reported residents as saying two passers-by were also injured, when the Toyota Corolla was driven into the Britons' Landcruiser.
One witness told the BBC: "I heard a big bang and then I fell to the ground.
"Once I looked I saw the British car had caught on fire and the power of explosion was so strong that some glasses in the nearby area were all broken.
"Then the Americans and Afghan forces cordoned off the area. I saw one of the British men, who was covered in the blood, taken away by the Americans."
Kandahar is a base for troops fighting Taleban militants
Afghan officials have warned they have intelligence suggesting further suicide attacks and are on high alert.
They told the BBC that militants were now using "Iraq-type" tactics.
The latest bombing comes less than a week after a suicide bomber drove himself into a Canadian military convoy, killing one Afghan and injuring another. The Canadian soldiers escaped unharmed.
In another recent attack, a man wearing military uniform drove a motorcycle into an army centre and blew himself up, killing nine people and injuring 36.
A spate of violence linked to militants has been widespread in Afghanistan since March, and has killed more than 1,000 people.