Turkey's Anadolu news agency claimed Moscow's deployment of mercenaries in support of Libyan warlord Khalifa Hafter included eight former members of DAESH in Libya.
Quoting Syrian sources, it says some of the mercenaries are from Deir Ez-Zor in eastern Syria.
According to sources the fighters also included elements from Iran’s Al-Quds Force.
Sources say each of the fighters is on a renewable monthly contract of between $1,000 and $1,500.
The contract will last for three months.
News of the deployment comes against the backdrop of Khafter's forces suffering loss of territory in Tripoli which had been under siege by his soldiers for more than a year.
Troops loyal to the internationally recognised government have been gaining steady ground against Hafter's men since April.
Russia, UAE, France and and Egypt back Hafter while Turkey and Qatar support the internationally recognised government.