In Baghdad insurgents armed with automatic rifles and rocket-propelled grenades have skirmished with US and Iraqi forces in Sunni Muslim areas of Baghdad, killing at least three police and seven insurgents.

Guerrillas attacked a police station in the northern area of Aadhamiya yesterday killing at least three policemen, police said.

In the western Amriya district, gunmen in several cars opened fire on a group of Iraqi National Guards deployed in the area. A guard at the scene said seven of the assailants were killed in the gunbattle that ensued and seven passersby wounded.

The policemen, discovered in an industrial area not far from the scene of some of the worst clashes in Mosul, appeared to have been killed by a bullet to the head, an AFP correspondent said.

Four of the corpses were also badly burned, the correspondent said.

Senior Iraqi and US military sources said they probably belonged to an Iraqi army unit that had joined US troops for a massive onslaught against insurgents in the country's third-largest city.

With US attack helicopters and soldiers covering them, Iraqi national guardsmen retrieved the bodies.

"These are not my men. They all have IDs from outside Baghdad. It seems they had been on leave and were returning to their barracks," said Lieutenant Colonel Ammar Abdelhadi.

A witness said he saw gunmen execute some of the men who were found dead.

"A group of five young men pulled up in front of the nearby veterinarian hospital, shot four men and dumped the bodies on the railway tracks," said Abu Abed.

Parts of Mosul were set ablaze last week when insurgents ransacked and torched about 10 police stations in coordinated attacks, panicking police who abandoned their posts.

Earlier at least 15 insurgents have been killed and 45 suspects detained over the last 24 hours while US-back Iraqi commandos Friday stormed a suspected rebel position in Mosul's old city, a warren of cramped streets and crumbling homes.

The operation took around an hour, and Iraqi military officials have promised similar assaults in the future.

The military is also searching for two missing Iraqi national guard officers feared kidnapped a few days ago by insurgents setting up road blocks elsewhere in the city.

The Islamist group of Abu Musab Al-Zarqawi claimed to have publicly killed two national guards in Mosul this week, according to an Internet statement on Friday.

Despite Saturday's grim discovery, Mosul Governor Duraid Kashmula insisted that the situation was under control and vowed to create a new police force after nearly 80 percent of his 5,000 police officers deserted in the November 11 attacks.

In the capital city, columns of thick black smoke rose above the area in the Sunni Muslim neighborhood of Aadhamiya and gunfire and explosions echoed over the rooftops. US Apache helicopters buzzed overhead.

US tanks were rolling through the streets. One armored convoy clattered past carrying away two wrecked US vehicles.

The fighting came a day after Iraqi troops backed by US soldiers raided a major mosque in Aadhamiya and clashed with worshippers. At least four people were killed in the raid on the Abu Hanifa mosque and nine wounded, the Muslim Clerics Association and witnesses said.

There has been a surge of unrest in Sunni areas of Iraq since US forces launched an offensive earlier this month to wipe out insurgents in the city of Falluja, west of Baghdad, which had become a guerrilla bastion.

In western Baghdad, a roadside bomb exploded as an Iraqi National Guard convoy drove past, destroying one vehicle, witnesses said. There was no immediate word on casualties.

Another roadside bomb was detonated as a US convoy passed it in central Baghdad. The US military had no details.

In a separate incident in the capital, an explosives-laden car blew up in the restive Palestine Street district as policemen were setting up a checkpoint, police sources told AFP at the scene.

Police officers at a nearby hospital said one policeman and a doctor and his wife were killed in the attack, which wounded 13 people, most of them policemen.

In Samarra, a Sunni Muslim city northeast of Baghdad reclaimed by coalition and Iraqi government troops a few weeks ago, two civilians were killed by a roadside bomb.

In nearby Tikrit, a police officer and a civilian were killed when unknown attackers opened fire on a police station, also wounding two people, police Lieutenant Colonel Muzher Khalaf told AFP.

Two policemen were also kidnapped on Friday and driven away towards the city of Kirkuk by armed attackers, the same source said.

Further north, in Baiji, a woman and four other civilians were shot dead by snipers after breaking a curfew imposed on the town after a recent spate of attacks, Khalaf said.

It was not immediately known if the five were killed by US or insurgent fire.

Elsewhere, the police chief of Babylon province survived a car bomb attack in the town of Hilla, south of Baghdad, although four people were wounded, including a policeman.

The attack was reportedly the third attempt on General Qais Hamza's life in the last month.

In the northern city of Kirkuk, US troops staged a raid in a neighbourhood suspected of housing militants involved in a string of attacks and nabbed 35 Iraqis, police said.

Lieutenant General Lance Smith, deputy commander of the US Central Command, said The United States plans to extend tours of duty of more troops in Iraq to increase force levels there through the planned January elections.

Smith added that additional troops may also be deployed from the United States if necessary to secure the country before the vote.

The number of troops would depend on the situation following the US-led assault to retake Fallujah, west of Baghdad, but it will be "probably an additional brigade's worth of forces," he said.

"We are talking mainly about extending some units," he told reporters at a press conference in Washington. "We will make further assessment as we get a little bit closer and understand what the impact of Fallujah has been in the entire country."

The US offensive in Fallujah set off a wave of insurgent attacks elsewhere in the Sunni Arab heartland north and west of Baghdad, as well as in the Iraqi capital. (AFP, Reuters)