Iraq's police, completely reformed after the 2003 US-led invasion, on Sunday apologised for acts committed during the rule of the dictator Saddam Hussein, on the eve of the force's 90th anniversary.

The statement came as Iraq grapples with a festering political row that has pitted the Shiite-led government against the main Sunni-backed bloc, raising sectarian tensions as minority groups have warned of the politicisation of the security forces.

"Security forces in the interior ministry apologise for the practices that took place during the former regime," the ministry said in a statement.

"They were forced to carry out practices that were not their duties."

It went on to say that the fledgling force, which has been rebuilt from the ground up in the past eight-plus years, were "the sons of the nation, carrying out their duties in order to implement the law and justice."

The statement came on the eve of the 90th anniversary of the police's 1922 founding, two years after Britain created the country under a League of Nations mandate, but a decade before it became fully independent.

Despite the apology for past acts, Iraq's security forces -- the police and army -- still regularly face criticism from rights groups for heavyhandedness, random arrests and abuses.

Interior ministry security forces, made up of city, oil and federal police as well as border enforcement officers and the facilities protection service, number around 650,000, according to government figures issued in October.

And even with their high staffing levels, multiple reports have assessed that they do not inspire public confidence and are unable to secure Iraq's cities and towns without help from the army.

"There is ... still a level of scepticism and mistrust towards the police in terms of law enforcement and human security," a UN report said last year.

And a separate report published in October 2011 from a US watchdog warned that senior officials in the interior and defence ministry had said "Iraqi police forces are currently unable to secure all of Iraq's urban areas without assistance from the Iraqi army."

Monday's 90th Police Day commemorations follow the marking of the 91st anniversary of the foundation of the Iraqi armed forces on Friday, during which mortars targeted the Green Zone while the army staged a parade inside.

The latest events highlighting the Iraqi security forces comes amid a spate of deadly violence against Shiite pilgrims, including a wave of bombings on Thursday which killed 70 people.

The violence has dealt a blow to US and Iraqi claims that domestic forces are able to maintain internal security, if not defend the country's borders.

US forces dismantled the Iraqi security forces after toppling Saddam Hussein in 2003 in a move later panned for having put hundreds of thousands of men with military training out of work and creating a potent recruitment pool for insurgents.