"The 18 Su-30s previously used by India and then returned, are in an aviation repair plant in Belarus and are on sale to potential buyers," deputy director of the Federal Service for Military-Technical Cooperation Alexander Fomin said.
The 18 fighters could be modernised before being sold, Ria Novosti news agency quoted Fomin as saying.
The Su-30MKI is India's lead fighter aircraft, and around 140 have been produced under license by Hindustan Aeronautics Limited (HAL), the report said.
Development of the Su-30 began in the 1980s for the Soviet Armed Forces, based on the Su-27UB conversion trainer.
The first batch of 18 Su-30s delivered to India were Su- 30MK and Su-30K standard, and were built to a lower specification than the later Su-30MKI. This meant that they did not have thrust-vectoring engine nozzles or canard foreplanes, enabling extra maneuverability, the report said.
Their avionics systems were also built to a lower specification than the later Su-30MKIs built by HAL, which included a high level of Israeli and French-built systems, the report said.