"We are in the process of negotiating this issue with them," Kupriyanov said in an interview with the Kommersant FM radio station, answering a question of whether Gazprom could supply Donbas with gas without the approval of Naftogaz.
"We have sent the relevant documents but have not received an answer yet," he added.
Naftogaz said earlier on Thursday that gas deliveries to Donbas had been halted as vital gas delivery infrastructure in the region had been destroyed by shelling.
Authorities of the self-proclaimed Donetsk and Luhansk people's republics in Ukraine's eastern Donbas region questioned the statement, saying Kiev had long considered stopping gas supplies to the region.
The republics turned to Russia for help, as their gas stocks would last only to Thursday evening in sub-zero temperatures. Russia’s Gazprom began pumping gas to the regions at 6:00 pm local time (3:00 pm GMT).
Hours later, Naftogaz said it had resumed gas deliveries to Donbas.