A handout picture released by the official Syrian Arab News Agency (SANA) on December 12, 2018 shows what Syrian authorities say are forensic experts digging out a mass grave in the area of Boukamal in the countryside of the Syrian province of Deir Ezzor on December 11, 2018. Image Credit: AFP/SANA

Damascus: Seven mass graves containing hundreds of unidentified bodies have been unearthed near the former Daesh group stronghold of Albu Kamal in eastern Syria, official news agency SANA said.

Most of the more than 100 bodies recovered so far at the site appear to "have been subjected to torture and ill-treatment before execution", it said, accusing Daesh of killing the victims.

Work was under way to retrieve the rest of the bodies from the graves in the eastern province of Deir Ezzor, SANA said in its report published late Tuesday.

It released a video showing forensic experts in protective clothing recovering remains, and corpses laid out on the ground in a row under white sheets.

A Syrian Red Crescent official said the main focus at present was identifying the remains already recovered which included those of several women.

"Exhumations will resume afterwards," the official said, asking not to be identified.

"The bodies show signs of torture and some were blindfolded and handcuffed."

Daesh has been held responsible for multiple atrocities during its reign of terror, including mass executions and decapitations.

In recent months, both Syria and Iraq have discovered a number of mass graves in areas previously occupied by the extremists.

Daesh proclaimed a "caliphate" over swathes of the two countries in 2014, but has since lost almost all the territory it once held.

Albu Kamal, which lies in the Euphrates Valley near the border with Iraq, was the last major town that Daesh controlled fully before losing it in November 2017.