MOSCOW – Hopes that Russia would get natural gas flowing again to shivering Europeans vanished like a winter’s breath yesterday when Moscow turned on the taps, then alleged hours later that Ukraine was blocking the shipments.

Ukraine in turn blamed Russia in the weeklong dispute, saying the Kremlin had demanded the Europe-bound gas go by a laborious route that would require Ukraine to cut off supplies to its own people.

European Union monitors brought in to keep tabs on gas flows in both countries weren’t saying who was at fault, but the EU was clearly angry at the crisis that has deprived millions of heat, light and even work.

“We are not entering a blame game here, but the commission reminds both parties of their responsibilities,” EU spokesman Johannes Leitenberger said. “The European consumer cannot, shall not, be held hostage to what is clearly a bilateral situation.”

Europe gets about 20 percent of its gas from Russia through pipelines that cross Ukraine. Russia stopped selling gas to Ukraine on Jan. 1 in a dispute over prices and debts, then stopped sending any gas into its vast pipeline system on Jan. 7, alleging Ukraine was siphoning off supplies destined for Europe.

The crisis raises high risks for both ex-Soviet countries. European countries that are already spooked by Russia’s increasing military assertiveness – underlined by last summer’s war with Georgia – could redouble their efforts to wean themselves from Russian gas. That would be a blow to Russia’s already-struggling economy.

Ukraine risks angering the EU, which leaders in Kiev want deeply to join. Its refusal to pay market prices for Russian gas – one of the roots of the dispute – would make it look like a beggar in the eyes of the West. And if Ukraine is forced to cut off gas shipments to its eastern region in order to deliver gas to Europe, that could hit hard at its industrial heartland, which is also the power base for the opposition to Kiev’s pro-Western leadership.

Russia’s state-controlled gas monopoly Gazprom said it began pumping gas to Europe yesterday. But EU officials said no gas was flowing and their monitors were not allowed full access to either nation’s gas control rooms; Russia later brought monitors to Gazprom’s central control room in Moscow.

Several European nations were growing desperate. Bulgaria has lost all of its gas supplies and has only two days worth of reserves. Slovakia, which has lost 97 percent of its gas supplies, said it was ready to restart an aging Soviet nuclear power plant despite EU objections.

Russian Prime Minister Vladimir Putin is to meet his Bulgarian and Slovakian counterparts in Moscow today.

Sales of electric heaters have soared and thousands of businesses in eastern Europe have been forced to cut production or even close. Millions of people have been affected by the heating crisis or involuntary layoffs.

Underscoring political tensions behind the gas dispute, Gazprom deputy head Alexander Medvedev accused Washington of encouraging Ukraine’s defiance. “It looks like they are dancing to music that is orchestrated not in Ukraine,” he said.

State Department spokesman Sean McCormack called the Russian accusation “bizarre … totally without foundation.”

Ukrainian energy adviser Bohdan Sokolovsky said Russia deliberately shipped the gas along a technically arduous route that requires Ukraine to cut out domestic consumers before it can deliver gas to the Balkans. He said a gas entry point on the Russian border at Sudzha and a gas pumping station near the Romanian border where Gazprom wants its gas delivered are not linked by an export pipeline.

Medvedev insisted that Russia deliberately chose Sudzha because it is an export pipeline with direct access to nations hit hard in the dispute, including Bulgaria, Romania and Turkey.

Ukrainian President Viktor Yushchenko accused Russia of using the dispute to try to wrest control of the pipelines from Ukraine.

Russia has accused Ukraine of stealing gas intended for Europe and only restarted supplies after a EU-led monitoring mission was deployed to gas metering and compressor stations across Ukraine. Ukraine has denied the charges, claiming that Russia has not sent enough so-called “technical gas,” which is needed to maintain pressure to send the rest of the energy to Europe.

The two nations disagree over who should pay for “technical gas.” Ukraine’s sprawling, inefficient pipeline network needs 21 million cubic meters of gas per day for transit – almost twice as much as the 12 million cubic meters consumed daily by Bulgaria.

Russia has used the gas dispute to push for new pipelines under the Baltic and the Black Sea that would bypass Ukraine. But EU officials say the crisis should encourage a search for independent energy sources and supply routes – such as the U.S.-backed Nabucco pipeline via Turkey – that would carry Caspian energy to Europe and circumvent Russia.

Relations between the two ex-Soviet neighbors have been strained since the 2004 Orange Revolution in Ukraine led to the election of a pro-Western government in Kiev. Ukraine’s efforts to join NATO and its support for the former Soviet republic of Georgia in its August war with Russia also angered the Kremlin.

Russia will not send natural gas to Ukraine for domestic consumption until the deadlock is resolved over what Ukraine should pay for Russian gas and what Russia should pay for using Ukraine’s pipelines.

Ukraine last year paid $179.50 per 1,000 cubic meters of gas and Yushchenko said yesterday that Ukraine will pay no more than $210 in 2009. Russia wants Ukraine to pay market price for gas, about the $450 that Europeans pay.