The antitrust watchdog launched a probe into the activities of Yuzhkuzbassugol, a subsidiary of Evraz Holding, and Raspadsky Coal following price fixing allegations.
Raspadsky Coal, Evraz Holding, and mining giant Mechel control over 50% of Russia's coking coal market between them.
Mechel has been fined 790 million rubles ($32 million), or 5% of its annual turnover, for violations of competition laws.
According to the antimonopoly service, Mechel abused its dominant market position by charging artificially high prices for its products, refused to sign contracts for deliveries, and supported a policy of price fixing.
The original probe into the activities of Mechel was launched after Prime Minister Vladimir Putin accused the company late in July of selling coking coal domestically at double the export price, and ordered the watchdog to look into the company's operations.
