The mass graves were found at an airbase on the outskirts of Hawija, a town occupied by the militants until early last month. It had been under Isis’ control since 2013.
Bodies wearing civilian clothes, fatigues and the orange jumpsuits Isis makes prisoners wear were among the dead, Kirkuk province governor Rakan Said told media. He did not say when the authorities would begin exhuming the bodies.
Local shepherd Khalaf Luhaibi who helped the security forces find the site told AFP that Isis brought prisoners to the area and shot them or poured oil over them and set them on fire.
More than 72 such sites have been discovered as US-backed forces across Iraq and Syria have succeeded in the full-scale fight to drive Isis out of its territory over the last year. It is estimated the graves could contain between 5,200 -15,000 people in total.
More than 95 per cent of Isis’ so-called caliphate has been reclaimed from the group, although advancing Iraqi coalition and Syrian Democratic Forces (SDF) troops face pockets of resistance.
There is still fierce fighting in the desert border region. Isis has also managed to recapture more than half of the Syrian town of al Bukamal, two days after the Syrian army declared it freed of militants.
The last town under Isis control in Iraq is Rawa, which came under attack by Iraqi forces over the weekend.
Although Isis’ proto-state project has almost entirely failed, analysts expect the group to morph into a full-blown insurgency across the two countries, and for Isis to step up terror attacks around the world in future.