KIEV, June 24 - Ukrainian businessman Dmytro Firtash is embroiled in a bitter divorce that could affect ownership rights over his multibillion-dollar commercial empire, including a company controlling natural gas supplies to Ukraine and the European Union, the Financial Times reported Friday.

Mr. Firtash this week hoped to boost the transparency of his portfolio of holdings, announcing that key assets, including Swiss-registered gas trader RosUkrEnergo, which he owns in partnership with Russia's Gazprom, had been consolidated under a new holding, Group DF (GDF).