The European Union could limit gas use to protect household energy this winter if Russia cuts off its gas supply to Europe over the Ukraine crisis.
Kiev claims Russia has threatened to halt its supply over fears Ukraine could siphon off energy destined for the EU as the pipeline runs through the country.
An EU source told Reuters: "In the short-term, we are very worried about winter supplies in south west Europe. Our best hope in case of a cut is emergency measures to protect households."
On Wednesday the EU is expected to discuss whether to impose new sanctions on Russia if they fail to pull its forces out of Ukraine. If it agrees to do so the sanctions are likely to be financial.
Were the Russians -as Barack Obama claims - weighed down by sanctions, or where the Ukrainians looking to cut their losses?
The new president of the European Council could be "very important" for David Cameron.