The US military turned up the heat on the flashpoint city of Fallujah with five air strikes in 24 hours, it said yesterday.

"Two US marines were killed in action and four US marines were wounded in action today," a US military spokesman said in a short statement released late on Thursday.

The incident took place in al-Anbar province, which houses the rebel hotspots of Fallujah and Ramadi, west of Baghdad, but the spokesman provided no further details about how the casualties happened.

"One 1st Infantry Division Soldier died and one was wounded when their vehicle was struck with an improvised explosive device near Balad at about 10:38 pm (1938 GMT)", it said in a statement.

Balad is a city 75km north of Baghdad.

Earlier three British troops and their Iraqi interpreter were killed Thursday in a suicide bombing, the first combat deaths since their regiment deployed in a dangerous US-run sector southwest of Baghdad last week.

Britain's Armed Forces Minister Adam Ingram said that, in addition to the four killed, eight other troops from Scotland's Black Watch regiment were wounded in the bombing at a roadblock that was followed by mortar rounds.

The Black Watch were redeployed late last month from the relatively peaceful southern city of Basra to relieve US troops preparing to fight insurgents in the violence-plagued city of Fallujah, west of Baghdad.

The attack occurred in the early afternoon as British troops crossed for the first time to the east bank of the River Euphrates, which the US Marines had turned over to the Black Watch, Ingram said.

The regiment had come under daily rocket and other attack from the other side of the river since it began redeploying October 27 to Camp Dogwood, a run-down base to the west of the insurgent-hit town of Mahmudiyah.

The deaths of the soldiers hit the front pages of British newspapers yesterday and commentators in several dailies warned that Prime Minister Tony Blair faced deepening trouble over his Iraq policy.

The 850-strong battle group had started full operations only two days earlier. A total of 73 British troops have died in Iraq since US-led forces invaded the country in March last year, 34 of them in combat.

US troops have massed around the two cities in recent weeks, which they believe are the nerve centres of rebel activity in Iraq, amid mounting expectations of a double-pronged assault.

The US-backed government of Prime Minister Iyad Allawi has pledged to crush pockets of resistance ahead of national elections promised by January.

To this end, US war planes launched five air strikes against suspected insurgent positions in Fallujah in the last 24 hours.

"Iraqi security forces and the 1st Marine Expeditionary Force continue to degrade and disrupt anti-Iraqi (insurgent) forces in the Fallujah-Ramadi area," a military statement said.

Starting at 4:40 pm (1340 GMT) Thursday and ending at 1:10 am Friday, planes supporting US marines on the ground destroyed suspected rebel fortifications and a weapons cache in the southeast and northern Fallujah, it said.

Since Monday, Multi-National Forces-West have also captured and destroyed large numbers of mortars, rockets and other explosives.

In Ramadi, the capital city of al-Anbar province, a marine operation discovered and disarmed a youth centre that had been rigged with explosives and found more that two tons of explosives hidden in a mosque.

"The discoveries were made during a sweep of the city looking for improvised explosive devices," the military said in a separate statement.

Fifty suspected insurgents were also netted in the sweep, it added.