The attack took place in the town of Tuz Khurmatu, about 70km (45 miles) south of Kirkuk, and also wounded nine officers on Sunday, district official Shahal Abdul said.

The town is in an area that was a source of dispute between the Iraqi government and the Kurdish minority.

This year has been one of the deadliest across Iraq, with thousands killed in terrorist attacks. More than 2,800 people have been killed so far in 2013.

Some 622 Iraqi people were killed in July and 1,395 people were wounded through to July 23, and the second-deadliest month of the year so far has been May, when 614 people died in attacks and 1,550 were wounded.

Although violence has decreased across the country since the peak of the insurgency in 2006 and 2007, bombings are still common.

The US-led invasion of Iraq left the Arab nation instable and insecure since 2003, and the string of violence continued despite the withdrawal of foreign military forces from the war-stricken country.

NTJ/SHI