The gas dispute between Russia and Ukraine is helping push up energy resource prices, with the price of a barrel of crude moving back above $50.
Gazprom, the Russian gas monopoly, has cut supplies to Ukraine in a dispute over how much the former Soviet state should pay for gas. The move also left supplies to Greece, Macedonia, Romania, Turkey and Croatia disrupted or cut off.
About 80% of the gas the EU imports from Russia comes through the Ukraine.
Russian prime minister Vladimir Putin ordered Gazprom to suspend deliveries through Ukraine in retaliation for alleged siphoning off gas bound for the EU.
The European Commission demanded an immediate settlement to the dispute.
"Without prior warning and in clear contradiction with the reassurances given by the highest Russian and Ukrainian authorities to the European Union, gas supplies to some EU member States have been substantially cut," it said.
"This situation is completely unacceptable."
Oil for February delivery climbed $1.66 to $50.47 before easing back on the New York Mercantile Exchange. It was also pushed up by tensions stemming from the Israel-Gaza conflict and concerns related to OPEC supply cuts.
Natural gas and heating oil prices were also higher.
