France accused Moscow on Tuesday of using energy supplies as "a weapon of war" after Russia's Gazprom cut deliveries to a major French customer and said it would shut its main gas pipeline to Germany for three days this week.
European governments are trying to coordinate a response to soaring energy costs for businesses and households and to fill storage facilities ahead of peak demand in the winter.
Western nations fear that Moscow is deliberately driving up gas prices to try to weaken their opposition to its invasion of Ukraine, a tactic Ukrainian President Volodymyr Zelenskiy on Monday dubbed "economic terrorism". Moscow denies the charge.
Nord Stream 1, the main conduit for Russian gas into Europe, has become a flash point in the dispute. Europe faces a further squeeze on supplies this week as Gazprom shuts off the pipeline for maintenance from Wednesday till the early hours of Saturday.
Kremlin spokesman Dmitry Peskov said on Tuesday technological problems caused by Western sanctions on Russia are the only thing standing in the way of supplying gas via Nord Stream 1.
But France's Energy Transition Minister Agnes Pannier-Runacher said: "Very clearly Russia is using gas as a weapon of war and we must prepare for the worst case scenario of a complete interruption of supplies."
She was speaking to France Inter radio after French utility Engie said it would receive less gas from Gazprom from Tuesday because of an unspecified contractual dispute.
Russia has been pumping gas via Nord Stream 1 at only 20% of capacity and there are fears that this week's outage could be extended.
Asked if there are guarantees that Gazprom will restart gas flows via Nord Stream 1, the Kremlin's Peskov said: "There are guarantees that, apart from technological problems caused by sanctions, nothing hinders the supplies."
'INSANE PRICES'
EU energy ministers will hold an emergency meeting on Sept. 9 to discuss the crisis.
Germany, Europe's largest economy, is open to discussing a price-cap scheme on gas supplies at a European level, a source in Italy said, citing a text message Germany's economy minister sent to his colleagues across the bloc.
The source said Robert Habeck sent a message to EU energy ministers flagging that Berlin was open to discuss the price cap at next week's meeting.
Italian Prime Minister Mario Draghi has been pushing for a price cap, and has also called for steps to decouple the cost of electricity from the gas price. Such a move would allow European households to get the benefits from electricity produced from cheaper sources such as renewables.
The chief executive of German energy firm Wintershall Dea said on Tuesday that current price levels meant demand for gas would fall in the long term.
"The prices we are having currently are insane. That is nothing even a gas producer is looking for because in the end, we are going to massively destroy demand for our product," Mario Mehren told reporters on the sidelines of a conference in Norway.
Benchmark Dutch wholesale gas prices rose on Tuesday afternoon after an initial retreat. The front-month gas contract was up 1.5% at 271 euros/MWh, off all-time highs hit last week but still trading at levels more than five times those seen a year ago.
(Reporting by Dominique Vidalon and Richard Lough in Paris, Giuseppe Fonte in Rome, Federico Maccioni in Milan, Holger Hansen in Berlin, Susanna Twidale in London, Vera Eckert in Frankfurt and Nora Buli in StavangerWriting by Keith Weir; editing by Jason Neely, Angus MacSwan and Gareth Jones)