Up to 30 gunmen in 10 cars attacked an Iraqi Interior Ministry building in Baghdad this morning.
"Two policemen were killed and five wounded," an interior ministry source told journalists, adding that the gunmen had used rocket-propelled grenades, mortars and automatic rifles.
Iraq's Shia and Kurdish-led government and US forces are facing a Sunni Arab insurgency which sees attacks on police and government forces on a daily basis.
Tensions between Sunni and Shia Muslims have been exacerbated by an impending referendum on a proposed new constitution for Iraq which Sunnis fear will reduce their influence.
Sunni Arabs were the dominant force in Iraqi politics under Saddam Hussein and before, despite accounting for only 20 per cent of the population.