Europe fears that Russia could extend scheduled maintenance to further restrict gas supplies to Europe, exacerbating a gas crisis that has triggered emergency government action and painfully high consumer bills.
The biggest single pipeline carrying Russian gas to Germany began annual maintenance on Monday, with flows expected to stop for 10 days, but governments, markets and companies are worried the shutdown might be extended because of the war in Ukraine.
The Nord Stream 1 pipeline transports 55 billion cubic metres a year of gas from Russia to Germany under the Baltic Sea. Maintenance lasts from July 11 to 21.
Operator Nord Stream AG confirmed the shutdown started as planned at 0600 CET and that gas flows would drop to zero a few hours later.
Last month, Russia cut flows to 40% of the pipeline's total capacity, citing the delayed return of equipment being serviced by Germany's Siemens Energy (ENR1n.DE) in Canada.
Canada said at the weekend it would return a repaired turbine, but it also said it would expand sanctions against Russia's energy sector.
Europe fears Russia could extend scheduled maintenance to restrict European gas supply further, throwing plans to fill storage for winter into disarray and heightening a gas crisis that has prompted emergency measures from governments and painfully high bills for consumers.