The United States on Tuesday urged Russia and Ukraine to settle their dispute over natural gas prices that prompted Moscow to shut off supplies in a move that was also felt in western Europe.

"It's something that we have raised with the Russian government," State Department spokesman Sean McCormack said at a daily news briefing.

"I believe our embassy has been in touch with Russian authorities," he said. "At the assistant secretary level here, we have been working the issue as well."

Expressing sympathy with Moscow's desire to move towards market prices for its natural gas, McCormack said Washington believe that "such a change should be introduced over time, rather than suddenly and unilaterally."

Russia's state-controlled energy firm Gazprom announced on Sunday that it cut off gas supplies to Ukraine, which depends on Russia for about one third of its gas imports, because Kiev had failed to accept a steep price hike.

The United States on Sunday criticized Russia for its decision to cut off gas supply to Ukraine, saying it created "insecurity" in the region's energy sector.

"Such an abrupt step creates insecurity in the energy sector in the region and raises serious questions about the use of energy to exert political pressure," McCormack said in a statement.

Source: Xinhua