The owner of National Basketball League champions the Illawarra Hawks has written to the sport’s international governing body accusing the league’s billionaire owner Larry Kestelman of conflicts of interest and asking that he be suspended from duties while an investigation takes place.

The letter, sent on Wednesday, escalates a messy dispute between Kestelman and Hawks owner Jared Novelly over the future of the competition and the money that flows into its 10 competing clubs.