US and Iraqi forces have carried out a major offensive in the northern Iraqi town of Samarra to try to retake control from insurgents.
US and Iraqi troops returned to Samarra earlier this month
US troops say around 109 militants were killed, but doctors at the main hospital spoke of 80 dead and more than 100 hurt, among them civilians.
An Iraqi minister said 37 insurgents had been captured in the assault.
An interior ministry spokesman said US and Iraqi troops were now in control of about 80% of the mainly Sunni town.
The US military said its troops had seized control of the town hall and police stations.
Iraq's National Security Minister Kasim Daoud told a news conference in Baghdad that the offensive was launched in response to a call for help from Samarra's residents to tackle the insurgents in their midst.
He went on: "We will spare no effort to clean all the Iraqi lands and cities from these criminals and we will pave the way through these operations, not only for the reconstruction, but also for the general elections."
The assault on Samarra, which lies on the main highway from Baghdad to northern Iraq, began overnight.
US and Iraqi government troops, backed by armoured vehicles and warplanes, advanced through the town neighbourhood by neighbourhood.
Insurgents responded with mortar and rocket-propelled grenade attacks, and small-arms fire.
One US soldier was killed and four wounded.
Some of the fighting took place close to a mosque that attracts
many Shia Muslim pilgrims to the region.
Residents spoke of cowering in their homes during a night of explosions.
The Americans said their troops had freed a Turkish worker named Yahlin
Kaya, who they say had been kidnapped and was being held hostage in the city.
The town is now said to be largely calm, but electricity and water are reported to have been cut off and staff at the main hospital said they were running out of supplies.
Samarra is one of several pockets in Iraq that over the past few months have fallen into the hands of insurgents.
A negotiated agreement three weeks ago that allowed US soldiers back into the city quickly unravelled.
The BBC's Caroline Hawley, in Baghdad, says that with elections due in less than four months, the interim Iraqi government is talking of trying to wrest back the whole of the country from rebels in the next few weeks.
She adds that the attack on Samarra may well be the beginning of a wider offensive.
In a statement, the US military said the offensive was in response to what it
called "repeated and unprovoked attacks by anti-Iraqi forces".
It aimed "to facilitate orderly government processes, kill or capture anti-Iraqi forces,
and set the conditions to proceed with infrastructure and
quality of life improvements for the people of Samarra".
The statement added: "Unimpeded access throughout the city for Iraqi
security forces and multinational forces is non-negotiable."
Meanwhile, in Baghdad, nine members of radical Shia cleric Moqtada Sadr's militia and three civilians are reported to have been killed during clashes with US forces in the Sadr City area.
Thursday saw a triple bomb attack in the city kill more than 40 people, most of them children.