Earlier on Thursday, Syrian SANA news agency reported a source in the Ministry of Industry who said that more than 300 Syrian civilians were missing following a Daesh attack on the Badiyah cement factory about 50km to the east of the capital Damascus.
"The company has informed the officials that over 300 workers and contractors have been kidnapped by Daesh militant group," the military source told the agency.
An administrator at the plant said the employees had been unreachable since Monday.
"We haven't been able to reach our family members since noon on Monday after an attack by Daesh on the factory," the AFP news agency quoted a resident as saying.
The so-called Syrian Observatory for Human Rights said "dozens" of staff were believed to have been kidnapped by Daesh from the Badiyah cement factory and taken to an unknown location.
The factory, which lies on the outskirts of Dumayr, has been the scene of fierce clashes between Daesh terrorists and Syrian government forces in recent days.
The Takfiri militants have sought to wrest control over Dumayr airbase and power plant, but have been unsuccessful so far.