Iraqi forces found a mass grave containing about 400 decomposed bodies in a newly-freed town northwest of Islamic State (IS) stronghold Fallujah, a source said on Monday.
During a mine clearing operation on Sunday in Shuhadaa district, security forces discovered the burial site believed to contain the bodies of both security members and civilians, Xinhua quoted the source as saying.
"Most of the bodies have been shot in the head, apparently by IS extremist militants," he said.
A security source from Anbar province said the area was the site of massive IS attacks on military bases in late 2014 through early 2015.
"Many civilians were also executed by the terrorist militants over various charges, including spying for the security forces or breaking the religious rules of the extremist group," the source said.
Two days ago, security forces and allied paramilitary Shia and Sunni units, known as Hashd Shaabi, entered Saqlawiyah near Fallujah, some 50 km west of Baghdad, and raised the Iraqi flag on the government building after several days of fierce clashes.
Iraqi Prime Minister Haider al-Abadi on May 23 announced the launch of a major offensive to retake Fallujah and surrounding towns and areas.
Government troops and allied militias have been fighting for months to reclaim key cities and towns in Anbar from IS militants, who attempted to advance toward Baghdad after seizing most of Anbar province.
Iraq is currently witnessing a fresh wave of violence since the IS wrested control of parts of the country’s northern and western regions in June 2014.
Many blame the current chronic instability, cycle of violence, and the emergence of extremist groups such as the IS on the US, which invaded Iraq in March 2003 under the pretext of seeking to destroy weapons of mass destruction (WMD) in the country.
The war led to the ouster and eventual execution of Iraqi president Saddam Hussein, but no WMD was found.