Iraqi forces stormed a police headquarters taken over by armed insurgents in western Iraq on Monday, ending a two-hour siege in which a town's police chief and four others were killed.

Gunmen disguised in police uniforms set off at least two explosions in mid-morning before overruning the Al-Baghdadi police headquarters in a compound that also houses the office of the town's mayor, officials said.

They seized 15 hostages, including the top police officer and the mayor.

Iraqi security forces finally overcame the insurgents more than two hours later, and found police chief Lieutenant Colonel Sadiq al-Obeidi and four others dead.

"Four security forces, including the chief of police and a civilian, were killed during the operation," said defence ministry spokesman Major General Mohammed al-Askari.

"The 15 hostages, including the mayor, are free now and they are in good condition," he said.

Iyad Arak, director of the main hospital in provincial capital Ramadi, also said five people were killed, including Obeidi, but gave no further details.

Military and police reinforcements had been sent to the town 150 kilometres (90 miles) northwest of Baghdad in predominantly Sunni Anbar province.

Meanwhile, a police officer in the town of Dolab, near Al-Baghdadi, said a similar attack was mounted on its police headquarters, with two suicide attackers blowing themselves up in front of the building.

A third suicide bomber was detained by police before he could set off his explosives, the major said. There were no police or civilian casualties as a result of the attack.

Anbar security forces imposed a vehicle curfew in the provincial capital Ramadi from 1:00 pm (1000 GMT).

The province was a key Sunni insurgent base in the years after the US-led invasion of 2003, but after 2006 local tribes sided with the American military and day-to-day violence has dropped dramatically.

However Anbar, and particularly its capital, has been the target of frequent attacks in previous months.

In June, at least three explosions near provincial government offices in Ramadi killed 10 people and wounded 15 others.

In January, a suicide bomber blew up an explosives-packed car carrying Anbar governor Qassim Mohammed Abid, but he was unhurt.

Provincial government offices were also targeted by attackers three times in 2010, and, on December 30, 2009, Abid lost his left hand in a suicide attack that killed 23 people and wounded 30.

Meanwhile, in the disputed northern province of Kirkuk on Monday, gunmen killed Colonel Serkot Abdul Ali Jabbari, the anti-terror chief in the town of Daquq, police said.

Authorities in Iraq's autonomous Kurdish region want to incorporate oil-rich and ethnically mixed Kirkuk into their three-province area, a move strongly opposed by authorities in Baghdad.

US officials persistently cite the unresolved row as one of the biggest threats to Iraq's future stability.

Despite a decline in violence, attacks are still common nationwide. A total of 185 Iraqis were killed in violence in September, according to official figures.