Ten Iraqi policemen were killed and 22 others wounded when they were targeted by a suicide car bomber as they headed home from protecting an oil installation on Wednesday, said a police commander.

"The policemen were travelling home on a bus when they were targeted by a suicide car bomber," in the south of the city around 5pm, said Lieutenant Colonel Ghazi Mohammad Rashid.

"All that was left of the bus were its seats, the officers' Kalashnikovs, and human body parts."

All the casualties were members of the Oil Protection Force, a department of Iraq's police, and had been working for the state-owned North Oil Company, added Rashid.

Half of the 31 000 strong oil protection force safeguard the nation's pipelines and the remainder provide security at refineries and gas stations across the country.

Wednesday's attack was the worst in Kirkuk since 11 December, when 55 people were killed and 95 wounded when a suicide bomber targeted a restaurant near the northern city, which is located 255 kilometres north of Baghdad.

Wednesday's suicide bombing was the latest in a series of deadly attacks that have shattered a recent improvement in security in Iraq.

It came four days after a suicide bomber dressed in military uniform infiltrated a gathering of US-allied Sunni fighters who were waiting to be paid, killing nine people and wounding dozens south of Baghdad.

That attack near Hilla also came at the end of a particularly deadly week in Iraq, where a series of bombings killed 70 people and wounded more than 300.

In recent weeks, the US military has played down talk of a rise in violence, as its soldiers prepare to withdraw from cities and major towns by June 30 and from the entire country by the end of 2011.

But five US troops and three members of Iraq's security forces were killed last Friday in the deadliest attack on American troops in Iraq for more than a year when a suicide truck bomber struck a police compound in Mosul, Iraq's second-largest city, which is also located in the north of the country.

Lieutenant General Lloyd Austin, the US army's second-highest ranking officer in Iraq, said in Baghdad on April 1 that recent "high-profile" attacks were not a signal that the security situation was worsening.

"We have driven down the level of attacks by violent extremists and terrorists," he told reporters. "In terms of the number of troops that I have had killed in action, I think the month of March was the lowest ever."

Security has improved dramatically since 2007 when Iraqi and US forces launched offensives against al-Qaeda militants with the help of local US-financed and trained Sahwa "Awakening" militias.

But insurgents are still able to strike with deadly results. A total of 252 Iraqis were killed in violence in March, almost the same tally as the previous month but up from January, when 191 Iraqis died in unrest.

AFP

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