Russia's RT Arabic television news network reported that Syrian soldiers made the discovery at the Panorama roundabout in the northwestern flank of the city, located about 455 kilometers (283 miles) northeast of the capital Damascus, and that the grave has the corpses of at least 1,500 civilians and military personnel in it.
The report added that responders are working to uncover and identify bodies at the site from clothes, fingerprints, documents or other special markers, Presstv Reported.
The mass grave makes it the largest one found in Raqqah so far.
Syrian Forensic Medicine General Director Zaher Hajo told Arabic-language and pro-government al-Watan daily in early January that Daesh Takfiris had executed 10,000 people and buried their bodies in mass graves across Raqqah.
He stressed that his colleagues had confirmed the presence of 4,000 bodies in one single grave.
Hajo went on to say that Syrian Health Minister Nizar Yazigi has ordered the formation of a committee in order to collect the remains of the victims and transfer them to the military hospital in Aleppo.
He stated that identification of the victims, using their teeth and bones, will start next week, stressing that he will chair the committee.
The so-called Syrian Democratic Forces (SDF) – a US-backed group of Kurdish and Arab forces – said on October 20, 2017 that it had “liberated” Raqqah after driving out Daesh terrorists from the city, which served as Daesh's de facto capital in the war-ravaged Arab country.
The US-backed forces later said the political future of the city and the province of the same name would be determined “within the framework of a decentralized, federal, democratic Syria.”
SDF spokesman Talal Silo said that the group would hand over the control of Raqqah to what he called “the Raqqah Civil Council.”
Syrian Minister of National Reconciliation Affairs Ali Haidar reacted by saying that Raqqah’s future could only be discussed “as part of the final political structure of the Syrian state.”
The so-called Syrian Observatory for Human Rights (SOHR) has, meanwhile, said that the SDF’s purported operations in Raqqah have killed civilians and damaged infrastructure in the city.
“When you’re killing around 1,200 civilians — nearly half of them women and children — and destroying 80 percent of the city, that’s not liberating Raqqah,” Rami Abdel Rahman, the head of the SOHR, told Arab News daily newspaper.