Two British security guards have been killed in an attack on a convoy in Basra, southern Iraq.
The bomb exploded on the outskirts of Basra
A bomb blew up near a convoy of British Embassy four-wheel drive vehicles south-west of the city on Saturday, UK officials said.
The Foreign Office said the attack, using a home-made bomb, had happened at 0630 BST on the outskirts of Basra.
The pair worked for Control Risks Group, which provides security for the consulate in Iraq.
A Foreign Office spokesman said: "A British Embassy convoy was hit by an improvised explosive device. Two security contractors have been killed."
A spokeswoman for Control Risks Group, which employs about 500 people in Iraq, said the company could not comment further on the guards' identity until next of kin had been informed.
Troops secured the area following the blast
One contractor working for the company was killed in an attack in Iraq about 15 months ago, she added.
Britain has about 8,500 troops in Iraq, mostly based in the south of the country.
At least 21 British civilians have been killed in Iraq since March 2004, according to the Foreign Office website.
It says: "The security situation is dangerous. The threat to British nationals remains high."
Basra is home to the British military headquarters and also the consulate general's office, which has about 20 employees.
BBC world affairs editor John Simpson said the convoy was heading through the south western edge of Basra when a roadside bomb went off in which two contractors, essentially bodyguards, were killed outright.
"We are told local people rushed out to help, including a couple of children who we are told were injured," he said.
Caroline Hawley, BBC News correspondent in Baghdad, said a second explosion, five minutes after the first, seriously injured two Iraqi boys. They were part of a crowd that had gathered around the scene of the blast.
She said the Foreign Office do not believe anyone else in the convoy was injured, but they would not comment on its role in the area.