"It is going to be conditions-based is what prime minister (Iyad) Allawi said and we agree with that," said General George Casey, the commander of US troops in Iraq, during a visit with soldiers in the restive northern city of Mosul.

"As the Iraqi security forces come on board, I think you will see the possibility for us to make our forces less visible."

He did not say what the other conditions were.

US President George W. Bush said Wednesday that troops would leave Iraq "as quickly as possible" but senior US officials have so far refrained from announcing a timetable.

Iraq's joint chief of staff General Babakir Zebari said he expects US troops to be scaled back and redeployed out of major cities by year's end.

Asked about the performance of Iraqi forces, Casey said: "They are doing fine."

The general pointed to the presence of Iraqi soldiers and police alongside US troops in tense Sunni Muslim areas like Fallujah, west of Baghdad, Samarra and Mosul to the north and Babil province, south of the capital.

"They are in the fight," he said.

"People are looking for an army to instantly emerge and that's not what it takes to build an army."

Casey said massive assaults against rebel strongholds like Fallujah in November combined with a recent increase in operations and raids in the run-up to Sunday's elections is starting to make a dent in the insurgency.

He said 15,000 insurgents were either killed or captured in 2004.

"It indicates we are a having a pretty good effect on them and I think you are going to see the results of that over the next few days," he said.

The general said Iraqis should be assured and not scared away from voting by the stepped up security measures, including the travel restrictions and large presence of US and Iraqi forces, tanks and armoured vehicles on the streets.

"The tanks, Bradleys and Strykers are a sign of security so they can feel fairly confident they can go out and vote in safety," he said.

Mounting US casualties in Iraq and the approaching elections have fueled the debate over when US troops would begin reducing their numbers.

Allawi said Tuesday it was "reckless and dangerous" to set a timetable for the pullout of US troops from Iraq, adding that any reduction must be gradual and contingent on the strength of Iraqi forces.

Casey estimated the current number of Iraqi police and soldiers at 130,000.

The fledgling forces have been the target of a relentless and crippling campaign of killings and attacks by insurgents. Their ability and willingness to stand up and fight has also been questioned.

In Mosul, Iraq's third largest city, the police force unraveled and local Iraqi army units suffered defections in the face of attacks by insurgents in November prompting the dispatch of thousands of extra US and Iraqi soldiers.

US troops in Mosul, one of the areas least prepared for elections and most vulnerable to attacks, will play a significant role in securing the outer limits of polling sites with Iraqi forces stationed on the inside.

"Millions of Iraqis are going to go out to the polls on Sunday because of soldiers like you around Iraq. Thank you, you are making a big difference," Casey told soldiers from the 1st Battalion, 24th infantry regiment hunkered down at a combat outpost in the New Mosul neighbourhood.

Half the building is severely damaged from suicide truck and car bombs that exploded nearby on December 29, killing one soldier and wounding 20.

Casey arrived in a convoy of Stryker combat vehicles accompanied by his deputy Lieutenant General Thomas Metz and Mosul-based US commanders.

The moment he arrived a large explosion went off nearby and a plume of black smoke rose in the sky, as soldiers control-detonated several roadside bomb devices.

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