Today's reports came two days after IS abducted 300 cement workers and contractors from their workplace in the areas of Dumeir just northeast of the capital Damascus.
The Britain-based Syrian Observatory for Human Rights said all those abducted have been released except for 30 people who were guards at the cement factory.
The IS-affiliated Aamaq news agency said most of the 300 were released after they were questioned to check whether they were all Muslims or included government supporters.