US and Iraqi soldiers are slowly seizing Falluja from insurgents on the day 2 of a full-scale assault, the US military says.
Troops have been advancing towards the centre, fighting rebels armed with rifles and mortars street by street.
US and Iraqi officials hope the assault – deeply unpopular with some Iraqis – will help prepare for January’s poll.
Some reports say US units have crossed the central highway in the heart of Falluja.
Earlier, a US tank commander said guerrillas were putting up a strong fight in the north-western Jolan district.