Officials from the European Union, Russia and Ukraine will meet on Monday in Brussels for further talks on the future of Russian gas supplies to Kiev and Europe.
They would prepare the ground for a second round of talks at ministerial level later this month, following a meeting last week in Warsaw, the European Commission said.
In Warsaw, EU Energy Commissioner Oettinger, Russian Energy Minister Novak and Ukrainian Energy Minister Prodan, agreed that gas supplies would not be interrupted while negotiations continued. Since then, however, the Ukraine crisis has deepened, with pro-Kremlin rebels in the east pressing ahead with plans for a referendum on independence from Kiev tomorrow.
On Thursday, Russia said Ukraine would have to pay up-front for future gas deliveries because of billions of dollars owed to Moscow.
The move was expected, but raises the stakes sharply given the 28-nation EU relies on Russia for about 25 per cent of its gas supplies and about half of that transits through Ukraine.
The European Commission said Monday's talks would continue on the agenda set in Warsaw, covering gas transit and supply, outstanding Ukraine debt and the price it paid, plus transparency and reliability of gas flows.
Monday's meeting coincides with a first trip to Kiev by European Council President Herman Van Rompuy and an EU foreign ministers meeting in Brussels which will discuss imposing possible additional sanctions against Moscow over the crisis in Ukraine.