Baghdad: Iraqi officials say a double bombing has killed seven people in a city north of Baghdad.

Police officials say the attack took place on Saturday morning, when a roadside bomb exploded in a commercial street in the northern city of Tikrit. Minutes later, a car bomb struck policemen who had arrived to inspect the first blast.

The officials say five policemen and two civilians were killed and 18 people were wounded in the bombings. Tikrit is 130 kilometre north of Baghdad.

A medical official confirmed the casualty figures. All officials spoke on condition of anonymity because they are not authorised to talk to the media.

Violence has spiked in Iraq since last April, a surge unseen since 2008. The relentless attacks have become the government’s most serious challenge.