US military officials said assailants used “small arms fire” on Thursday. The crew of the helicopter gunship spotted an assailant fleeing into a house, which troops later raided.

A total of 11 men were detained, including a “significant” former Iraqi government official, said a military spokesman from a base in Tikrit, hometown of ousted Iraqi president Saddam Hussein.

Overnight, huge explosions could be heard at the base as US troops demonstrated their firepower in what occupation authorities described as a “show of force” involving tanks and Bradley fighting vehicles.

In related news, three American soldiers were wounded in separate attacks in the northern city of Kirkuk and Falluja, west of Baghdad.

Two of them were hurt when a roadside device exploded as a six-vehicle convoy drove through central Kirkuk, said an Iraqi police officer. The blast destroyed a pick-up in the convoy and two soldiers were taken to hospital.

In Falluja, a US soldier was wounded when a convoy was hit by an explosive device, said a witness adding, a vehicle was also damaged.

The US military said it had no information on either incident.