Doubts have emerged over reports that Isis has massacred 175 civilians captured at a cement factory near the Syrian capital.
Reuters quoted Syrian military sources reporting the killings on Friday, days after officials said more than 300 workers were missing from the Al Badia Cement Company.
The news agency later said the source had been "misattributed" and warned that the report was unconfirmed.
Russian state media also reported the massacre, saying sources on the ground were “almost certain” a mass execution took place.
Sputnik News claimed 175 people were murdered “because of their religious affiliation” but that some fled and others were allowed to leave.
Russian special forces are supporting Bashar al-Assad's troops in Syria, where the Russian air force is backing their military campaigns with air strikes.
The cement factory lies north-east of Damascus in an area of countryside targeted by an Isis advance in recent days.
Syrian state media reported that officials in the nearby town of Jeiroud saw around 125 of the abducted workers being transported in Isis vehicles, heading towards Tal Dakweh.
“We haven’t been able to reach our family members since noon on Monday after an attack by Daesh [Isis] on the factory,” one resident of Jeiroud told the AFP news agency. “We have no information about where they are.”
The Syrian Arab News Agency said a “reconciliation committee” had been handed 106 employees on Wednesday.
Amaq Agency, which publishes Isis propaganda, posted footage claiming to be from inside the cement factory.
It showed diggers and lorries parked in a deserted depot, with Isis fighters milling around office buildings and the group's black flag fluttering at the entrance.
The body of a man dressed in military fatigues was shown lying on the ground.
According to Al Badia’s website, the plant started production in 2011 and employs 360 people.
Fierce clashes have erupted in the area in recent days between Isis, government forces and Syrian rebels.
The jihadists reportedly sought to seize control of the nearby Dumeir air base and a power plant but were pushed back.
