At a conference on metallurgy in the Volga area city of Nizhny Novgorod, Prime Minister Vladimir Putin asked the Federal Antimonopoly Service (FAS) and the country's top prosecutors to pay special attention to the company, which sold commodities abroad at prices twice as low as domestic and global ones in the first quarter of 2008.
"We should find out what is happening there," Putin said.
Mechel CEO Igor Zyuzin was unable to attend the conference due to illness.
The latest reports quoted a medical source in Moscow as saying that Zyuzin was admitted to a Moscow cardiology clinic on Wednesday.
"Zyuzin was admitted with heart problems and is undergoing treatment in a Moscow Medical Academy clinic," the source said.
Mechel has several metal plants in Russia, Romania and Lithuania. It unites producers of coal, ore, nickel, steel, and highly-processed steel products for the domestic and foreign markets.
In 2007, the company's output totaled 21.2 mln metric tons of coal and 5.1 mln tons of rolled products.