KIEV, July 2 - Ukrainian national oil and natural gas company Naftogaz Ukrayiny has reiterated allegations that Russian oil company Tatneft has illegally transferred an 18.3% stake in Ukrainian oil company UkrTatNafta to two other companies.

UkrTatNafta runs an oil refinery in Kremenchuk in Ukraine's Poltava region.

Naftogaz Ukrayiny "cannot understand" operations with UkrTatNafta shares and dealings between AO Tatneft and ING Bank Ukraine, Naftogaz Ukrayiny spokesman Oleksiy Fedorov said.