BAGHDAD: Iraqi officials say gunmen have killed three policemen in an attack on a security checkpoint north of Baghdad.

Police officials say the attack early Monday took place when gunmen in two speeding car opened fire on a security checkpoint in Taji area, about 12 miles (20 kilometers) north of Baghdad. Three other policemen were wounded in the attack.

A local medic confirmed the casualties. All officials spoke on condition of anonymity because they were not authorized to talk to the media.

Violence has dropped across Iraq, but insurgents frequently attack security forces in an attempt to destabilise the country.