Gas prices in Europe have surged after Russia's state-owned energy firm said it would cut shipments through a major supply route.
Gazprom said it was turning the tap off to the Yamal pipeline, which runs to Germany via Poland, following fresh sanctions imposed by Moscow against European gas companies.
These include one of its former subsidiaries Gazprom Germania and Europol Gaz, which owns the Polish section of the pipeline.
Germany's economy minister Robert Habeck expected the fall in Russian gas deliveries could be compensated for on the market, albeit at a higher cost.
He said: "On the whole, the situation is escalating.
"It's becoming evident once again that Russia is using energy as a weapon."
As a result of the latest retaliation by Moscow, future contracts linked to the TTF hub, the European wholesale gas price benchmark, have seen marked increases and will further add to the burden on households and businesses.
Although German gas storage is around 40% full, it is still low for the time of year and stocks need to be built up in time for winter, when heating demand will rise and global supply shortages will hit.
Kaushal Ramesh, senior analyst at consultancy Rystad Energy, said: "Storage levels are currently sufficient to last through most of 2022, even if Russian flows were to stop instantly, barring any unexpected weather events - but the outlook for winter 2022 supply is now a lot more pessimistic."
Gazprom said in a statement: "A ban on transactions and payments to entities under sanctions has been implemented.
"For Gazprom this means a ban on the use of a gas pipeline owned by Europol Gaz to transport Russian gas through Poland."
Moscow's sanctions came just a day after Ukraine shut down the flow of a Russian gas to Europe from a pipeline, which runs through the country, blaming interference by occupying Kremlin forces.
It was the first time exports via Ukraine have been disrupted since the invasion.