The officer was standing in front of the local offices of the Department of Social Welfare in the eastern Mosul district of al-Faisaliya when "unknown gunmen" opened fire and killed him, police in Mosul told the German Press Agency dpa.

Also on Sunday, in a predominantly Christian district in an eastern district of the city, a band of armed men abducted a teacher, police added, without providing any further details.

The teacher was at least the fourth civilian to be abducted from the area in the past 24 hours. On Saturday night, police told dpa that armed men had abducted three civilians, including a Christian woman, from the al-Akha' weh al-Bakr district in the east of Mosul.

Mosul and its environs are among the most religiously and ethnically diverse areas of Iraq, and among the most prone to violence, despite successive security pushes that police say have netted hundreds of insurgents.

On Sunday morning, police found two corpses in the south of the city, they told dpa. The bodies were turned over to forensic scientists for identification.

Sunday's attacks on Iraqi security forces in Mosul followed two deadly gun battles in Mosul Saturday night. In one incident, insurgents killed two Iraqi police officers in the city centre, police said.

In another, police arrested 23 men suspected of belonging to al-Qaeda in Iraq after a firefight in the al-Darkazaliya al-Jaza'ir district of eastern Mosul on Saturday night.