Naftohaz Ukrainy CEO Andri Koboliev told reporters in Brussels, Censor.NET reports referring to Ukrinform.
"As we currently see it though without plain confirmations, Gazprom supplies its gas to those areas. In our opinion, it means that along with the seizure of the territory the Russian side has also grabbed a market share and tries to retain it," Naftohaz CEO said.
He said he had no precise information on how the payments for consumed gas were collected in the occupied territories.
"We do not have this documented, but we know that Gazprom is trying to earn money there," Koboliev noted.
He recalled that Naftohaz had supplied gas to the occupied territories in the Donbas until February 2015 but stopped it because of the numerous terrorist threats and attacks.
Earlier, Prime Minister Arsenii Yatseniuk said that Ukraine would not buy Russian gas at $212 per thousand cubic meters as it could be purchased for $200 from the EU.