The United States warned Russia not to use energy costs as an instrument of political coercion, after Moscow scrapped its last gas price discounts for Ukraine, Agence France-Presse reported.
Russian Prime Minister Dmitry Medvedev earlier announced the move, effectively raising the price by $100 to $485 for every 1,000 cubic meters of gas.
Asked about the decision, White House spokesman Jay Carney warned "markets should determine energy prices. A country should not use supply and pricing terms as tools of coercion to interfere in Ukraine or anywhere else," he said.
He said Washington was encouraging its allies on Ukraine's western borders to reverse natural gas flows to let the Kiev government access more supplies if needed.
Carney's warning mirrored that of Secretary of State John Kerry on Wednesday before Russia's latest move as he attended a U.S.-EU Energy Council meeting in Brussels.
"No nation should use energy to stymie a people's aspirations," Kerry said.
In another move, Russian energy giant Gazprom demanded that Ukraine's Naftogaz take immediate steps to pay for previous gas deliveries, valued at over $2.2 billion.
Tensions between Moscow and Kiev are running high after a pro-Western government came to power in Kiev following the fall of president Viktor Yanukovych and Crimea’s annexation to Russia.