Four British soldiers and a Kuwaiti interpreter were killed Thursday in an ambush in southern Iraq, the British military said.
The patrol struck a roadside bomb and was hit by small-arms fire about 2 a.m. in the Hayaniyah district west of Basra, 340 miles southeast of Baghdad, British military spokeswoman Capt. Katie Brown said.
Another British soldier was seriously wounded, Brown said.
It was the biggest loss of life for British forces since Nov. 12, when four were killed in an attack on a Multi-National Forces boat patrol on the Shatt Al-Arab waterway in Basra, Iraq's second-largest city.
Prime Minister Tony Blair, addressing the press after 15 sailors and marines landed in London after being held captive by Iran for nearly two weeks, said the battle against terrorism in Iraq remained a top priority.
"We return to the sober and ugly reality of what is happening through terrorism in Iraq, terrorism designed specifically to thwart the will of the international community," Blair said.
"Now it is far too early to say that the particular terrorist act that killed our forces was an acted committed by terrorists that were backed by any elements of the Iranian regime, so I make no allegation in respect of that particular incident," Blair said.
Thursday's deaths raised to 140 the number of British forces to die in Iraq since the March 2003 invasion and to 109 the number killed in combat.
Iraqi police officials in Basra said the British patrol had earlier detained 1st Lt. Haider al-Jazaeri of the Interior Ministry's Major Crimes unit, and were on their way back when they hit the roadside bomb. Gunmen then opened fire from three directions, causing more casualties, the officials said without providing a breakdown.
British troops backed by helicopters cordoned off the area for about two hours after the attack, the Iraqi officials said.
Britain is set to withdraw about 1,600 troops from Iraq over the next few months and hopes to make other cuts to its 7,100-strong contingent by late summer.