Olexy Gudyma, an advisor to Ukrainian Prime Minister Yulia Tymoshenko on energy issues, said a deal could be agreed by Christmas Day, which in the Russian Orthodox world falls on Wednesday, January 7.
"The main thing is that a process is underway, that the delegations are preparing for meetings and the process is continuing," he told Echo of Moscow radio in an interview.
"I think that by Christmas all the contracts for the coming year will be signed."
His comments came after Russian energy giant OAO Gazprom (GAZP.RS) earlier Thursday cut off its gas supplies to Ukraine in a row over prices and debts, triggering concern over supplies of Russian gas to Europe.
Gazprom spokesman Sergei Kupriyanov also called for talks to be renewed but said that the negotiating team from Ukraine state gas company Naftogaz had left Moscow.
"All our management are in place and we are ready to continue talks with our (Ukrainian) colleagues. But they have not shown a desire to come and sit at the same table," he said in a separate interview with Echo of Moscow.
He accused Ukraine's leaders of sending the Naftogaz negotiating team to Moscow with the express orders not to sign a deal with Gazprom by midnight, which would have prevented the cut.
"Their mission was conflict, to drag things out as long as possible and to enter the new year without a contract."
In Kiev, President Viktor Yushchenko's representative on energy issues, Bogdan Sokolovsky, countered that it was the Russian side who were holding up the resumption of talks.
"Our delegation is ready to resume negotiations at any moment. But we have still not received an official response from Russia," he said.