"As of today, the records received by the Investigative Committee give grounds for opening a criminal case against Uralkali shareholder Suleiman Kerimov and detaining him," Pavel Traulko, representative of the Belarusian Investigative Committee, said.
Vladislav Baumgertner, the chief executive of Uralkali, was detained Monday and charged with abuse of power, RIA Novosti said.
Uralkali and Belaruskali, a Belarusian potash producer, had been working together in a cartel and using one trading company for all their exports.
In June, Baumgertner accused Belaruskali of selling potash outside their cartel agreement, and in July, Uralkali pulled out of the cartel.
The association collapsed as a result and potash prices fell dramatically.
The Belarusian authorities said Monday that Baumgertner's actions had caused damage to the public interests of Belarus.
Monday's arrest angered the Russian government, which summoned the Belarusian Ambassador.
Potash, mined and manufactured salts mostly used in fertilizers, makes up around 8 percent of Belarus' exports.