"A soldier was killed yesterday just after 5:00pm at a forward operating base near Balad," Sergeant Robert Cargie, a spokesman for the 4th Infantry Division, said.

"The base came under mortar attack and one GI (general infantry) was killed by shrapnel, while two others were wounded."

Cargie said US forces had detained six people in connection with the attack, but gave no further details.

The death of the soldier raises to 329 the number of US troops killed in action since Washington launched the war to overthrow Saddam in March. Of those, 214 have been killed by guerrilla attacks since major combat was declared over in May.

The US military meanwhile raided a Sunni mosque in western Baghdad and said it had seized arms and explosives in an operation that sparked an angry Muslim protest after Friday prayers.

More than 1,000 worshippers at the al-Tabool mosque denounced Thursday's raid in an emotional demonstration and accused US troops of trampling on the Quran.

"American soldiers entered the mosque with their shoes on and with machine guns in their hands," the imam, Abdulsatar al-Janabi, told Reuters, adding the raid had lasted five hours.

"They trampled on the holy Quran, beat up some of the worshippers and stole computers and a donations box," he said. Others claimed that a page was torn from the Quran.

Protesters screamed and cried, chanting: "God is great" and "America is the enemy of God."

Brigadier General Mark Kimmitt, a US military spokesman, said US troops had conducted the operation after a tip off from Iraqis and netted a wide array of weaponry to be used against occupying forces facing a relentless insurgency.

"Over recent months, the US 1st Armored Division has received numerous reports from Iraqis that the al-Tabool mosque was being used for criminal and terrorist activities," Kimmitt told a news conference Friday.

"US forces, led by the Iraqi Civil Defence Corps and the Iraqi police therefore conducted a cordon and search."

He said troops had found several sticks of high explosives, hand grenades, AK-47 rifles, rocket-propelled grenade launchers and thousands of rounds of ammunition.

"There is clear evidence from what we seized that this mosque was being used for things other than free religious expression," Kimmitt said.