The Iraqi military says around a hundred decapitated bodies have been found in a mass grave in the recently-retaken town of Hamam al-Alil. Most, they say, were reduced to skeletons.

Iraqi forces are fighting to recapture Mosul, ISIL’s last major stronghold in the country. In its two years in Iraq, the militant group has often circulated photos and videos online of massacres it has carried out.

Now, it seems, the extremists are on their way out, but leaving a trail of destruction in their wake.

Their scorched earth policy is causing environmental and health issues as well as added distress to local citizens, aid agencies warn.

The United Nations has condemned the move to burn oil wells, particularly near Al-Qayyarah, saying the environmental pollution is adding “complexity and danger” to the humanitarian crisis.