The European Union has demanded that Russia and Ukraine solve their row over gas deliveries and stop jeopardizing supplies to the bloc, dpa reported.
In the strongly-worded statement, released overnight to Saturday, the 27-member bloc, which is Russia's biggest gas customer, "calls for an urgent solution to the commercial dispute on gas supplies from the Russian Federation to Ukraine, and for an immediate resumption of full deliveries of gas to the EU member states."
The statement was released by the Czech government, which holds the bloc's rotating presidency.
Russian natural gas volumes pumped via Ukrainian pipelines to Romania, Hungary, Poland, Slovakia and Romania all were down overnight, with Romania registering a 33-per-cent cut in deliveries.
The drops in supply come after Russian gas monopolist Gazprom cut off gas deliveries to Ukraine on Thursday in a row over contracts.
The EU initially tried to stay out of the dispute, calling it a commercial matter between two non-EU companies, but the fall in supplies forced its hand.
"Energy relations between the EU and its neighbours should be based on reliability and predictability. Existing commitments to supply and transit have to be honoured under all circumstances," the statement said.
Ahead of the cut-off, both Russian Prime Minister Vladimir Putin and his Ukrainian counterpart, Yulia Tymoshenko, called the head of the European Commission to accuse the other of starting the trouble and promise that supplies to Europe would not be hit.
"The EU regrets the fact that assurances of the reliability of energy supply have not been met and will continue to monitor the situation closely," the EU's statement said.