Three British soldiers whose regiment had recently moved northward to support an expected American-led assault on Fallujah were killed in a suicide bombing on Thursday, British officials said.
Meanwhile, the medical relief agency Doctors Without Borders announced that it was ending its operations in Iraq because of deteriorating security.
Britain's Armed Forces Minister Adam Ingram, told the House of Commons that three soldiers of the Black Watch infantry regiment were killed in the attack.
The Black Watch regiment is one of the oldest and most storied in the British military. The soldiers' deaths could put new pressure on Prime Minister Tony Blair, whose justifications for joining the war in Iraq have faced intense criticism at home.
An Iraqi interpreter was also killed, and eight other British soldiers were wounded, said MajOR Charlie Mayo, a British Army spokesman in Basra. Mayo said that further details would be released once the families of the dead soldiers had been notified.
Last month, the Black Watch regiment had redeployed from the relatively peaceful southern city of Basra to reinforce US troops massing for a possible attack on Fallujah. The soldiers' deaths bring to 73 the number of British military personnel who have died in Iraq since invasion last year.
Meanwhile, officials for Doctors Without Borders said the decision to leave Iraq had been forced by the "extreme risks" faced by aid workers in the country.
CARE International suspended its operations in Iraq after its national director, Margaret Hassan, was abducted last month.
On Tuesday, her captors said they would turn her over to the group led by the Jordanian militant Abu Musab al-Zarqawi within 48 hours if Britain did not withdraw its troops from Iraq.
More than 160 foreigners have been kidnapped and at least 30 killed since the US-led invasion last year.
Doctors Without Borders, which was awarded the Nobel Peace Prize in 1999 for its humanitarian work, is a veteran of the world's toughest conflict zones.
But with the violence here surging, the group's foreign staff left Iraq four to five weeks ago and is now based in Amman, Jordan, said Arjan Hehenkamp, operational director for the group in Iraq.
Now, the Iraqis who have remained will be let go.
"It is clear that we cannot maintain a professional relationship with them in the long term," Hehenkamp said.