There is very little chance of Ukraine signing a new gas transit deal with Russia's Gazprom before Jan. 1, Naftogaz Chief Executive Andriy Kobolyev told a conference Wednesday.
He also said he had no final confirmation that Russian representatives would attend another round of talks on a new agreement Thursday.
Ukraine is a key transit route through which Russian gas reaches Europe but a current deal between the two post-Soviet countries expires at the end of the year.
"It (the probability of signing by Jan. 1) is gradually approaching zero, but we are optimistic," Kobolyev said.
Time is running out to hammer out a new agreement, with relations battered since Moscow annexed Crimea from Ukraine in 2014 and backed separatist fighters in a conflict in the eastern Donbass region.
Moscow has previously said the transit tariffs proposed by Ukraine to ship Russian gas through its territory next year were too high, a claim dismissed by Kyiv.