It comes after a full-scale assault on the city, approved by the Iraqi prime minister, was launched on Sunday.

US and Iraqi officials hope the assault will help prepare the way for elections in the country in January.

Up to 3,000 rebel fighters are thought to be holed up in Falluja, which has been a hotbed of resistance to the US-led occupation of Iraq.

Overnight, Iraqi soldiers gained control of the main railway station in Falluja.

In the run-up to the assault, troops also took two bridges and the city's main hospital.

They are now said to be advancing street-by-street towards the city centre.

Curfew

But there are concerns about thousands of regular people who remain in the city.