Russia has completely halted gas supplies to Europe via a major pipeline, saying repairs are needed.
The Russian state-owned energy giant, Gazprom, said the restrictions on the Nord Stream 1 pipeline would last for the next three days.
Russia has already significantly reduced gas exports via the pipeline.
It denies accusations it has used energy supplies as a weapon of war against Western countries.
The Nord Stream 1 pipeline stretches 1,200km (745 miles) under the Baltic Sea from the Russian coast near St Petersburg to north-eastern Germany.
It opened in 2011, and can send a maximum of 170 million cubic metres of gas per day from Russia to Germany.
The pipeline was shut down for 10 days in July – again for repairs, according to Russia – and has recently been operating at just 20% capacity because of what Russia describes as faulty equipment.
The president of Germany’s network regulator has said the country will be able to cope – if Russia resumes delivery in the coming days.
“I assume that we will be able to cope with it,” Klaus Mueller told Reuters. “I trust that Russia will return to 20% on Saturday, but no one can really say.”
Meanwhile according to BBC reports heavy fighting is raging in the Kherson region as Ukraine is trying its territory occupied by Russian forces.
“Heavy fighting is continuing, our soldiers are working around the clock,” said Vitaliy Kim, who heads the neighbouring Mykolaiv region.
Ukraine earlier said it had broken through Russia’s first line of defence.
But Russia said Ukrainian troops had been defeated during a failed attack.
Kherson became the first major Ukrainian city to fall into Russian hands in the opening days of Moscow’s invasion that began on 24 February.