A mass grave of 16 bodies, each shot in the head, has been found in northern Iraq, in an area once controlled by the Islamic State (formerly known as Isis).

The bodies were found blindfolded and bound in Kobachi, part of Saadiya District, 87 miles north-east of Baghdad, which used to be a former IS stronghold.

It is believed the killings took place before Iraqi security forces drove the terror group out of the area in late November 2014.

"The joint excavation crews have discovered 16 bodies of men who were blindfolded and had their hands tied behind their backs," the district chief Mohammed Mulla Hassan, from the Patriotic Union of Kurdistan party, told Reuters.

"They were found in the Kobachi area and they were executed in the past few months," he added.

Hassan blamed the killings on Sunni jihadists affiliated to IS, who were forced out of the area by militias supporting the Shi'ite-led coalition government in Baghdad.

IS had taken Kobachi as part of its rampage to extend the Islamic caliphate across northern and western Iraq last year.

Last month the Iraqi army, Shi'a militia groups, and members of the Sunni Jubouri tribe united to launch a new offensive against Isis on the strategically located Iraqi town of Dhuluiya.