Amid fears that fighters opposed to the US-appointed government would step up attacks to derail the elections, violence gripped the country on Wednesday, with two assassination bids in Mosul, a car bomb in Baghdad and a string of other incidents.
The launch of the huge operation in the area south of Baghdad on Tuesday came as the international community voiced its support of the tight timetable for Iraq's first post-Saddam Hussein elections.
In Washington, Defence Secretary Donald Rumsfeld said the United States would send an unspecified number of extra troops to Iraq to beef up Iraqi forces before the January 30 vote.
Some 5000 American, British and Iraqi forces took part in the operation that began with raids on villages north of the city of Hilla, the US military said.
The force looked set on Wednesday to make its way northwards to the areas blocking access to the capital.
The towns of Latifiya, Yusufiya, Mahmudiya and Isqandariya have seen fighters carrying out a string of deadly attacks in recent months.
'Reconstruct and rehabilitate'
The operation followed a massive assault on Falluja, the largest since last year's US-led invasion. The city had been resisting US control since April and its recapture was seen as essential to organising the promised January elections.
Most of Falluja's 300,000 inhabitants fled the city before the assault began on 8 November, but with a few pockets still not under full control, humanitarian needs inside the city remain unknown.
US marines are no longer meeting
resistance in Falluja
An Iraqi Red Crescent team set off from Baghdad for Falluja but it was unclear how much access it would be granted to the devastated city.
Falluja's hospital is not functioning and doctors are looking to "reconstruct and rehabilitate" the facility according to director Dr Rafi el-Esawy. Victims of the US onslaught on the city have been transferred to hospitals in Baghdad, he said.
An AFP reporter embedded with US marines and who toured the devastated city on Wednesday said US forces were no longer meeting any resistance.
But fighters remained active elsewhere.
Mosul erupted in violence after
the US-led attack on Falluja
The leader of a special Iraqi commando force sent from Baghdad to back US-led efforts against fighters in Mosul, the country's third-largest city, escaped an assassination attempt, US military officials. US forces returned fire and killed the four attackers.
The US military said five bodies were found in Mosul, bringing to 20 the number of corpses found there in recent days, many of them Iraqi soldiers.
Fighters ambushed a convoy of Kurdish militiamen as they travelled to Mosul on Wednesday, killing three of them and wounding nine others, hospital sources in the nearby town of Arbil said.
Meanwhile, in western Baghdad, a bomber driving a car killed two other people, police said, adding that the victims may have been foreigners.
A group of Iraqi national guardsmen carried out raids in western Baghdad on Wednesday afternoon, searching for suspects and weapons.
The soldiers said they arrested eight suspected fighters, and seized a large quantity of weapons and thousands of dollars.
Also in Baghdad, a US convoy came under attack by an explosion from improvised explosive device in the city's Al-Kanal area. No reports on casualties have been confirmed.
Falluja was badly damaged by the
US military offensive
Unfazed by the violence, the Iraqi interim government is pressing ahead with preparations for the elections.
More than 200 Iraqi political parties have been approved for participation in the polls, electoral commission chief Abd al-Husain al-Hindawi said.
With the deadline for presenting full electoral lists only a week away, parties and organisations were in the final stages of discussions to form alliances before the official launch of the campaign on 15 December.
In January, Iraqis are set to elect 275 deputies to a national assembly, as well as 51 members of the Baghdad provincial council and 41 members for each of the 17 other regional councils.