"As a result of June 6 and 8 aerial strikes on targets belonging to IS fighters, IS field commanders Abu Omar al- Belgiki and Abu Yasin al-Masri were killed" in Deir Ezzor, a province held mostly by IS forces, the defence ministry said in a statement carried by the Interfax news agency.
The ministry said that around 180 fighters were killed, and that 16 military vehicles were destroyed along with weapons stores.
It said the strikes took place after Russian forces using drones spotted preparations by IS fighters to break through the defences of a garrison held by Syrian government forces in the city of Deir Ezzor.