Russia accused Ukraine on Wednesday of holding Europe "hostage" by blocking efforts to resume gas supply to desperate people and demanded forceful EU intervention to get deliveries moving again.
Ukraine hit back, charging that Russia had deliberately chosen a gas transit route through Ukraine that made it technically impossible for shipments to Europe to pass through the country's Soviet-era pipeline network.
While millions of people in Europe began a second week of suffering as a result of the sudden cutoff of Russian gas supply, leaders of two EU states travelled to the region to confront Russian and Ukrainian political leaders.
"Our European partners really have become hostage to the dispute between Russia and Ukraine," Russian Prime Minister Vladimir Putin said as he met the prime ministers of Bulgaria and Slovakia at his residence outside Moscow.
"No country has the right to take other countries hostage by taking advantage of its transit role," said Putin.
"European Commission officials could use their influence over Ukraine more to ensure the supply of gas," he added.
Hours earlier, Russia's state-run gas giant Gazprom issued a statement charging that Ukraine had refused a request for the transit of nearly 100 million cubic metres of Russia gas to the Balkans and Slovakia.
Gazprom said the gas taps were open in Russia and the necessary pipeline pressure was attained but Ukraine's state gas company Naftogaz had declined to allow the gas into its pipeline network for forwarding to European customers.
A Naftogaz spokesman did not deny this but said Gazprom's proposed transit route would not work for technical reasons.
"We cannot technically send the gas to where they want it to go," Naftogaz spokesman Valentyn Zemlyansky told AFP in Kiev.
Gazprom said it wanted to pump the gas through its station at Sudzha near the Russia-Ukraine border, the same facility where initial efforts to re-start the flow of gas to Europe faltered on Tuesday.
In Kiev, Ukraine Deputy Foreign Minister Konstantin Yeliseyev said Russia had scripted its apparent efforts to resume shipping gas to Europe in such a way as to ensure that Kiev bore the blame for its failure.
"The so-called submission of gas ... was nothing more than decoration," Yeliseyev was quoted by news agencies as saying.
The prime ministers of Bulgaria and Slovakia, two of the EU states hardest hit by the cutoff in Russian gas, met Putin at his residence and both afterwards also said they felt like "hostages."
"The worst thing for me is that millions of citizens of Europe feel like hostages and hundreds of thousands of people are really suffering," Bulgarian Prime Minister Sergei Stanishev told Putin.
Slovakian Prime Minister Robert Fico told Putin: "We don't want to work out who's right. This is a bilateral dispute."
But Fico, in a heated exchange with Ukrainian Prime Minister Yulia Tymoshenko in Kiev before he travelled to Moscow, called on her to meet with Putin to find a way out of the crisis.
Fico said later to Putin: "I told Tymoshenko that Ukraine is losing the trust of its European partners because of its behaviour."
At around the same time, Tymoshenko told a press conference in Kiev that she was ready to talk with Putin and had requested a meeting with the powerful Russian prime minister.
"We are waiting for the Russian government's answer," she said. "The process of negotiations must move from the Gazprom-Naftogaz level to the level of governments."
European countries rely heavily for gas on Russia, which accounts for around 40 percent of the European Union's imports.
The current crisis began on New Year's Day when Russia cut gas supply to Ukraine after the two ex-Soviet republics failed to reach agreement on Kiev's payment of arrears and on new prices for 2009.
That cutoff was followed a week later by shortages among Russia's customers in Europe. After accusing Ukraine of cutting off export avenues to Europe -- a charge denied by Kiev -- Russia halted all transit to Europe through Ukraine.