Witnesses said the casualties were from various sections of Iraqi society, who had been at the funeral to express their condolences. Mainly Sunni Arab insurgents have staged increasingly audacious attacks on Shi'ite and official targets in their relentless campaign to topple a US-backed government and stall efforts by the Shi'ite majority to form a new cabinet.

In Baghdad, insurgents posing as policemen killed a police chief, stopping his truck at a fake checkpoint, asking his name then shooting him in an attack claimed by al-Qaeda followers. Later police found the bodies of four Iraqi soldiers shot dead and dumped by insurgents in western Iraq, adding to two grim discoveries of 41 bodies -- some shot and others beheaded -- in the country's Sunni heartland earlier this week. The US-backed interim government has set up a new Iraqi police force, army and security service, often trained by foreign instructors. But many say insurgents bent on bringing down the US-backed government can easily penetrate their ranks.

Mosul, Iraq's third largest city, with a mixed population of mostly Sunni Arabs and Kurds, has had a surge in violence since last November when coordinated guerrilla attacks on police forced them to desert. Dozens of people with serious injuries were taken to hospital after today's bombing, witnesses said.

Tensions have risen in Iraq's north between the three main groups that populate the area, the Shi'ites, the Kurds and the Sunnis. The Kurds, who want to extend an autonomous region in the north, dominate the area and have encouraged those who fled under Saddam Hussein to return home. In Kirkuk, newly returned Kurds trying to reclaim land clashed with Iraqi police. Two national guards were wounded, police said.

In the capital, insurgents targeted police. Lieutenant-Colonel Ahmed Obeis, travelling to work at Salhiya police station in central Baghdad, was shot dead along with two other policemen while one guerrilla filmed the attack. "On March 10 an al-Qaeda team set up a checkpoint in the Ilam district and lay in wait for an officer in the Interior Ministry intelligence branch who used to investigate and harm mujahideen," al-Qaeda in Iraq said in an internet statement.

"When he pulled out his identity papers the mujahideen riddled him with bullets, killing him." In southeastern Baghdad, another policeman, Iyad Abed, was shot dead by gunmen on his way to work. In the town of Rutba on the highway to Jordan in western Iraq, the bodies of four Iraqi soldiers were found, hospital sources said, adding the men had been shot around five days ago.

Guerrillas target those working for the interim government, US forces or building companies helping to rebuild Iraq. They have often impersonated police to carry out attacks. Yesterday, insurgents dressed as police detonated a suicide truck bomb outside a Baghdad hotel used by foreign contractors, killing at least two people and wounding at least 40, including 30 Americans.

"It is just a matter of paying money and anyone can infiltrate the police force," a police official told Reuters. The insurgents' ranks have been boosted by frustration at the US occupation, shootings of Iraqi civilians by troops and foreign contractors, and by abuse of prisoners in US-manned jails. Reuters