In pictures: Falluja assault

1 of 10 US-led troops have been advancing towards the centre of Falluja as part of their assault on the rebel stronghold.

2 of 10 US and Iraqi forces have been hammering the city with air strikes, artillery and tank fire.

3 of 10 Between 10,000 and 15,000 US and Iraqi troops are involved in the operation, codenamed Dawn.

4 of 10 City residents have described conditions there as hellish.

5 of 10 The joint US-Iraqi forces have taken over the city's main railway station...

6 of 10 ...and begun rounding up suspects as bitter street fighting with rebels raged on.

7 of 10 It is unclear how many fighters are in the city. Clerics in Falluja have been urging them to "rise up" and fight.

8 of 10 Fighters have been seen roaming the streets inside Falluja, bearing weapons and belts of ammunition.

9 of 10 The joint-assault force came under heavy fire as it began its advance into the city.

10 of 10 As the assault began on Monday night, explosions and flares lit up the sky.