Mass grave containing 150 anti-Isis Sunni tribal fighters discovered by Iraqi officials

Albu Nimr had fought running battles against the Islamic militants, recently being pushed out of Hit as the terrorist organisation advanced

Pro-Iraqi forces regroup south of Baghdad on the route toward Fallujah (Getty)

The bodies of 150 Sunni tribesmen who fought against Isis have allegedly been discovered in a mass grave outside Ramadi in central Iraq, just under 70 miles from the capital Baghdad.

The discovery, which raises the spectre of further atrocities, comes as Isis (also known as Islamic State) publicly executed at least 40 Sunni fighters and security personnel yesterday in Hit after parading them in front of the town’s residents.

Isis militants are believed to have taken around 150 men from their villages to the city of Ramadi in Al Anbar province and killed them before burying them, an official in a police operations centre and another security official told Reuters.

The dead men are believed to belong to the Sunni Albu Nimr tribe, which has opposed the advance of Isis fighters.

It is thought the atrocities are an attempt to prevent the Sunni tribes joining a wider coalition against the militants as they have done in the past. In 2007 many of the clans in Anbar province joined the ‘Sahwa’ or ‘Awakening’ and revolted against al-Qaeda.

"Early this morning we found those corpses and we have been told by some Islamic State militants that 'those people are from Sahwa, who fought your brothers the Islamic State, and this is the punishment of anybody fighting Islamic State'," an eyewitness told the news agency.

Tribal sheikhs from Albu Nimr say both sets of victims were among more than 300 men aged between 18 and 55 who were seized by Isis this week.

Ramadi is a key objective for Isis. Fallujah, the next city west of the Euphrates, has been held by the militant force for the past year .

The capture of Mosul, the biggest city in northern Iraq, four months ago saw thousands of Christian, Shia and Sunni Muslims and Yazidi civilians executed, along with Iraqi army prisoners.