The US military claims to have killed hundreds of insurgents in four days of fighting in Falluja, and says it is pushing the rest of the rebel-held town's defenders into a smaller and smaller corner.

But it has acknowledged that victory in Falluja will not end the insurgency, a point underscored by a car bomb in Baghdad and heavy fighting in the northern city of Mosul on Thursday.

The operation in Falluja had been ?very successful?, with ?hundreds and hundreds? of insurgents killed or captured, General Richard Myers, chairman of the Joint Chiefs of Staff, said on Thursday.

However, he added: ?If anybody thinks that Fallujah is going to be the end of the insurgency in Iraq, that was never the objective, never our intention, and even never our hope.?

On the eve of a fourth night of fighting, US forces in Falluja claim to have cleared out the insurgent stronghold in al-Jolan district, handing it over to Iraqi security forces. They say they have captured key municipal buildings and driven the last fighters into a small enclave in the south of the city.

Estimates of the rebel dead run to 600, although US officials say an accurate figure is hard to obtain because of the use of air strikes and other heavy ordnance.

Resistance has reportedly been lighter than expected, however, and US officials have said many of the several thousand insurgents thought to have been in the city fled before the fighting, including the most-wanted Jordanian militant Abu Musab al-Zarqawi.

US troops claim to have rescued an Iraqi taxi driver taken as a hostage 10 days ago and held shackled in a basement, while Iraqis moving through the city claimed on Wednesday to have discovered ?hostage slaughterhouses? with records of those abducted.

The US military said on Thursday 18 US soldiers and marines had been killed in the attack, while reporters in the military's Landstuhl Regional Medical Centre in Germany, where heavily wounded troops are often evacuated, have reported that more than 210 casualties have arrived in the past week.

The Dubai-based al-Arabiya news channel reported military sources as saying that two marine Super Cobra helicopters were hit by gunfire and forced to land in separate incidents.

Even as US forces secured Falluja, however, insurgents struck at police stations and other government targets across Iraq in an apparent effort to take pressure off the embattled city.

The US military reported a second day of heavy fighting in Mosul, where police called for support from US forces against dozens of fighters armed with rifles and rocket launchers who attacked their stations.

Although guerrillas have raided police stations before, the past few days have witnessed large-scale assaults aimed at taking over whole neighbourhoods, albeit temporarily.

Residents of the Baghdad suburb of al-Dura, home to a power plant and refinery, said 50 rebels had swarmed up the road from the Sunni Arab enclave of Latifiya to the south and fought with police on Tuesday and Wednesday in an apparent attempt to shut down the capital's electricity supply.

Insurgents have also wreaked havoc with more traditional tactics, setting off a car bomb in a central Baghdad square on Thursday that killed at least 10 people.

In the last week, guerrillas have struck in virtually every big city in central and northern Iraq, including Mosul, Ramadi, Samarra, Tikrit, Baaqouba, Bayji and Baghdad.

Additional reporting by Dhia Rasan

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