The talks, which opened in Brussels yesterday, seek to resolve a dispute that has become increasingly fraught since Russia cut supplies to Ukraine in June.
Moscow is demanding that the new pro-Western government in Kiev pay sharply higher prices in advance for new deliveries after it ran up what Moscow said was an unpaid bill of USD 5.3 billion.
That supply cut has heightened concerns that Europe, which gets about a third of its gas from Russia of which about a half transits via Ukraine, could be badly affected by the dispute this winter.
The gas talks are expected to resume today evening, sources close to the negotiations said.