BAGHDAD - At least 31 US Marines were killed in a US transport helicopter crash near the western Iraqi city of Rutbah, according to military and media reports yesterday.

It is the highest number of US fatalities to result from a single incident since the US first occupied Iraq almost two years ago.

Earlier yesterday the US military in Baghdad confirmed the crash saying it happened overnight as the helicopter was transporting soldiers from the 1st Marine Division, headquartered in Fallujah.

Witnesses said the helicopter appeared to have been hit by a surface-to-air missile and exploded on hitting the ground.

A second helicopter also came under fire but was able to reach safety, the witnesses said.

A further five US soldiers were killed in two other incidents yesterday, bringing the day's death toll to 36, the highest since March 23, 2003, when 31 soldiers died.

Four US soldiers were killed yesterday during clashes with insurgents in the western province of Anbar, while a fifth soldier died in an attack on a military patrol north of Baghdad.

Meanwhile seven people died when a car bomb exploded at a police station in the northern Iraqi city of Kirkuk yesterday, a police spokesman said.

Three policemen, two Iraqi soldiers and two civilians died and three policemen were injured, police said.

Witnesses spoke of two more car blasts, one near a city marketplace and another outside the town near a US patrol, but there were no immediate reports of casualties.

Seven soldiers were injured in two separate car bombs targeting US convoys on the main road leading to Baghdad International Airport yesterday morning, the US military said. The bombs exploded within four hours of each other along a route that has frequently been targeted by insurgents.

One Iraqi was killed and two were wounded in a firefight between US troops and insurgents in the centre of the city of Ramadi, hospital sources said.

In the village of Bu Nimr, 20 kilometres from Ramadi, US troops rounded up 40 Iraqis on suspicion of helping insurgents carry out attacks against US convoys.

Saboteurs blew up a school designated as a polling station for Sunday's elections, witnesses said. No one was injured in yesterday's blast at a girls' school north of Baghdad. A number of would-be polling centres have come under attack by insurgents seeking to derail Sunday's vote for a new National Assembly. - Sapa-AFP