Russia's Gazprom has said it was halting another turbine in the Nord Stream 1 pipeline to Germany and the flow of gas, already at just 40% of capacity, would fall by another half from Wednesday.

The new blow to supply comes at a moment of high tension as Russia and the West exchange economic blows in response to Moscow's actions in Ukraine. The European Union has accused Russia of resorting to energy blackmail, while the Kremlin says the gas disruption has been caused by maintenance issues and the effect of Western sanctions.

Gazprom said output from Wednesday would fall to 33 million cubic metres per day - just half of the current, already reduced, supply.

Politicians in Europe have repeatedly warned that Russia could cut off gas flows this winter, a step that would thrust Germany into recession and lead to soaring prices for consumers already grappling with higher prices for food and energy.

Russian President Vladimir Putin warned the West this month that continued sanctions risked triggering catastrophic energy price rises for consumers around the world.

Russia is the world's second largest oil exporter after Saudi Arabia and the world's largest exporter of natural gas. Europe imports about 40% of its gas and 30% of its oil from Russia.

Gazprom resumed gas flows via Nord Stream 1 last week after a 10-day maintenance break, but only at 40% of the pipeline's capacity - a level Russia has said it was forced to lower volumes to in June because of the delayed return of a turbine being serviced in Canada.

European politicians have challenged that explanation, with Germany saying the turbine in question was not meant to be used until September.

Gazprom said earlier today it had received papers from Siemens Energy and Canada about the first turbine, but added that there were still problems.

"Gazprom has studied...the documents, but has to acknowledge that they do not remove the previously identified risks and raise additional questions," it said in a statement.

"Additionally, there are still open questions from Gazprom regarding the EU and UK sanctions, the resolution of which is important for the delivery of the engine to Russia and the urgent overhaul of other gas turbine engines for the Portovaya compressor station."

The Kremlin said earlier that Moscow was not interested in a complete stoppage of Russian gas supplies to Europe, which is rushing to fill its underground storage before the winter season.

It said Gazprom was not to blame for the storage risks, reiterating its line that Europeans are suffering the consequences of sanctions that they themselves imposed against Russia.