After the announcement of the end of the massive assault on Iraq's once rebel-held city of Fallujah, the US military on Sunday released the latest casualties with 38 US troops killed and 275 wounded in the operation.

The numbers are a big increase from the ones disclosed on Saturday, with 22 US soldiers killed and 178 injured.

The military said in a statement that the death toll included three soldiers who died of "non-battle injuries," adding that 60 of the wounded have already been returned to duty.

According to the statement, some 1,000 insurgents were killed and 450 to 550 captured in the Fallujah operation.

There is no word on civilian casualties, which residents have said were heavy.

Iraqi national security advisor Qassim Dawood told a press conference on Saturday in Baghdad that the assault on Fallujah hadended.

But the US military noted late Sunday that it could take several more days of fighting before the city is secured.

Witnesses said US troops were still battling small bands of militants scattered in buildings and bunkers across the Sunni Muslim stronghold, while Iraqi troops were painstakingly clearing weapons and fighters from every room of Fallujah's estimated 50,000 buildings.

Aid groups on Saturday expressed their concerns over the fate of the civilians. The Iraqi Red Crescent (IRC) encouraged both fighting parties to facilitate the movement of its medical teams.

While the US army said it was targeting suspect sites with careful measures to avoid civilian casualties, a resident of Fallujah, who managed to flee the city, said corpses were lining the streets.

Thousands of families fleeing the city had to live in makeshiftshelters outside Fallujah that lack basic necessities despite the cold weather and the probability of spreading diseases, especiallyamong children.

"There are thousands of old people, women, and children who need aids like shelter, food, water, and medical care, and unknownnumber of injured civilians are inside Fallujah without any care,"said IRC spokesman Ahmed Al Rawi.

While fighting in Fallujah is coming to an end, the US troops stepped up attacks at anti-US insurgents in other Iraqi cities.

In the northern city of Mosul, US and Iraqi government troops are locked in battles with insurgents on Sunday.

The battle was aimed at wresting back control of a police station, which was taken by rebels earlier in the day.

The clashes were mainly centered on the city center with an exchange of fire, witnesses said.

Parts of Mosul, the third largest city in Iraq, were now virtually in rebel hands after insurgents stormed and took controlof several police stations last week.

The police chief of the city was sacked after the rebel insurgence and reinforcement of the Iraqi National Guard was dispatched.

However, the US military in the city said despite the police station attack, order and security have been restored.

Also on Sunday, US tanks covered by helicopters rolled into another northern Iraqi city of Baiji, some 200 km north of Baghdad,and exchanged fire with insurgents, who attacked the US forces first with small arms and rocket-propelled grenades.

Media reports gave different figures of casualties.

Baiji, the biggest oil refinery town in Iraq, sits at a key route linking oil transportation between Iraq and Turkey.

Several buildings in the town were destroyed, but the Baiji refinery was spared in the fighting and remained operational.

The interim Iraqi government has imposed a curfew on the town for an indefinite period due to the surging violence since earlierthis week.

In Baghdad, at least two heavy explosions were heard on Sunday night, followed by a spate of gunfire.

The blasts could be heard near central Saadoun Street and heavygunfire followed, witnesses said.

They added that smoke rose over the site of the blast, which appeared to have been caused by a rocket.

However, there were no immediate reports on the cause of the blasts. The US military had yet to make a comment.

Anti-US insurgents often fire mortars and rockets at hotels used by foreign journalists and security contractors in central Baghdad.