A bomb has exploded in a police station in the Iraqi city of Hilla, killing the commander of an Iraqi special police force responsible for tackling the growing violence.

Colonel Salam al-Maamuri, head of the US-trained Iraqi police special intervention team, died along with his deputy in a blast that left at least eight other officers injured, Iraqi police said on Friday.

"He was transferred to hospital after the bomb went off, but he died on the way," said Lieutenant Kadhem Shamari, as US troops arrived to seal off the brigade's headquarters in the southern city of Hilla.

Doctor Haidar Timimi at Hilla's main hospital confirmed the death and said eight wounded officers were receiving treatment.

Lieutenant-Colonel Michelle Martin-Hing, US military spokeswoman, said the bomb appeared to have been packed with ball bearings to render it more lethal.

Al-Maamuri had previously survived several assassination attempts.

His squad was set up with US support to counter fighters opposed to the US presence in the country in an area south of Baghdad, including a region that became notorious as the "Triangle of Death".

In recent months, Iraqi police have born the brunt of violence directed at Iraq's US-backed coalition government, but it is unusual that bombers would manage to plant a device inside a headquarters building.

Last week, US-led forces revealed that 4,000 Iraqi police officers have been killed over the past two years.

Sadr's order

Shia cleric Moqtada al-Sadr has ordered his Mahdi Army militia not to take part in the sectarian violence and told those who had killed Iraqis to "repent".

"There are rumours that there are groups or persons from the Mahdi Army attacking the Iraqi people with no right to do so," al-Sadr said in a statement distributed by his office in the city of Najaf.

"It is not proved so far but, if proved, I will declare their names and will renounce them with no fear or hesitation."

Tens of thousands of young men have joined the Mahdi Army in the three and a half years since Saddam Hussein was overthrown.

In August 2004, al-Sadr's armed supporters fought fierce battles with US forces in Najaf and and the Sadr City district of Baghdad but their leader has since chosen to follow a more political route.

According to US commanders, many of the estimated 23 militia groups in and around Baghdad are linked to or protected by al-Sadr's Mahdi Army, a loosely organised force of young Shia fighters.

The US military have said that Shia militias as the biggest single threat to the stability of Iraq and they are waiting to launch an operation to clear Sadr City of armed men.

Photo Caption

Colonel Salam al-Maamuri