Syria conflict: 230 bodies 'found in mass grave' in eastern Deir al-Zour province

The tribe is from Deir al-Zor province has around 70,000 members

Isis has made huge profits from captured oilfields (Getty Images)

More the 230 bodies have been found in a mass grave in Syria’s eastern Deir al-Zor province, a group monitoring conflict in the country said on Wednesday.

Members of the extremist group Isis have not claimed responsibility for the deaths, but the dead are believed to be members of the al-Sheitaat tribe which had battled the militants, the Britain-based Syrian Observatory for Human Rights said.

The tribe is from Deir al-Zor province and numbers about 70,000. If confirmed, their deaths would bring the number of Sheitaat members killed by the Isis to over 900.

Omar Abu Layla, a spokesman for the moderate rebel umbrella Free Syrian Army group in Syria's east, told Reuters that Sheitaat tribespeople had discovered the mass grave as they returned to their homes. Isis, which calls itself the Islamic State, is occupying the area and had given them permission to return.

"This is a message from Daesh that if there is any attempt at revenge, your fate will be the same as your relatives," he said, using a derogatory Arabic acronym for the Islamic State group.

Over the course of this year, Isis has seized swathes of Syria and Iraq, and currently controls all but a few pockets of Deir al-Zor province.

The group has used revenue from the province’s oilfields to fund its operations, but faces pressure since a US-led coalition started launching air strikes against it in Syria in September.

The gruesome discovery comes after the militant group had killed some 700 members of the Sheitaat tribe in August - the majority of them civilians - over the preceding two weeks after conflict flared when the militants took over two oilfields.

The Observatory, which has tracked violence on all sides of the nearly four-year-old conflict, said beheadings were used to kill many of the tribe's members.

Isis fighters are currently battling Syrian President Bashar al-Assad's forces near Deir al-Zor city for a military air base that is one of the government's last strongholds in the country's east.

The Britain-based Syrian Observatory for Human Rights also revealed today that more than 120,000 fighters supporting Syrian President Bashar al-Assad have been killed in the country's civil war since it began in 2011.

In 2011, Syria's conflict began as a peaceful protest movement calling for reforms in quickly but descended into civil war after a government crackdown.

In total, more than 200,000 people have been killed and millions more have fled their homes.

The unstable situation means exact death tolls are difficult to verify, but the figures calculated by the Observatory are widely regarded as credible. The United Nations estimated in August more than 190,000 people had died in the conflict.

Additional reporting by Reuters