European leaders have voiced their fury at Russian president Vladimir Putin, after he threatened "extreme measures" against the gas supply to Europe if the Ukraine crisis is not resolved.
Putin has accused Ukraine of not paying its $2.2 billion gas debt to Russia. Moscow has almost doubled the gas price it charges Ukraine since the overthrow of pro-Kremlin premier Viktor Yanukovych, plunging Kiev's economy further into crisis.
In a letter to the leaders of 18 European countries, Putin said Russian exporter Gazprom could cut off supplies to the Ukraine, through which much of Europe's supplies run.
“We fully realise that this increases the risk of (Ukraine) siphoning off natural gas passing through Ukraine's territory and heading to European consumers,” Putin's letter said.
But, it warned, if Ukraine does not settle its bill, Gazprom will demand advance payment, or it "will completely or partially cease gas deliveries.
"Undoubtedly, this is an extreme measure."
Around 30-40% of Europe's gas flows through Ukraine. Several European countries depend entirely on Russia for gas supplies, including Sweden, Finland, Estonia, Latvia, Lithuania and Bulgaria.
On Friday, the European Commission called on Russia on Friday to respect its gas commitments and urged Ukraine to respect gas transit commitments, in its first public response.
"We expect Russia to respect its supply commitments and we expect Ukraine to respect its transit commitments," Commission spokeswoman Sabine Berger told reporters, adding that gas supplies from Russia to the European Union were stable.
Similar condemnation came from the US. “We condemn Russia's efforts to use energy as a tool of coercion against Ukraine,” State Department spokeswoman Jen Psaki said.
On Friday, Putin's press officer Dmitry Peskov said a decision on gas supplies lies solely with Gazprom, according to Kyiv Post.