(Reuters) - A Belarusian court on Friday rejected a second appeal by the chief executive of Russian potash producer Uralkali, despite calls for his release by Russia, and ruled he be kept in detention pending investigation into alleged abuse of power, his lawyer said.

Vladislav Baumgertner, CEO of the world's top potash producer, was detained on August 26 while visiting the Belarusian capital, further straining relations in a trade feud between Russia and the ex-Soviet republic after the collapse of a potash sales cartel.

A district court on September 6 refused to release Baumgertner, 41, pending investigation, and a city court in Minsk on Friday rejected a second appeal for him to be freed on bail.

"They turned it (the appeal) down. We will appeal further," lawyer Dmitry Goryachko told journalists.

(Reporting by Andrei Makhovsky; Writing By Richard Balmforth; editing by Mike Collett-White)