Northern Iraq's oil hub city is plagued with tensions among its rival Kurdish, Turkmen and Arab communities.

Assailants gunned down Bassem Abbas al-Bayati, a policeman of Turkman origin, as he returned home on Saturday in the centre of the city, said police Lieutenant Colonel Kamel Ahmad.

A Kurdish peshmerga fighter, Karwan Jumaa Hussein, was killed the same way in northern Kirkuk, and two Sunni brothers, Shehab and Bilal al-Mufurdji, were shot dead in an eastern district of the city late on Friday.