The German government said on Friday it was "examining" the Kremlin's decree that payments for Russian gas must now be made in rubles, which has raised fears supplies will be cut.

Berlin and Western partners have insisted that their contracts with Russian companies state clearly that their payments can be made exclusively in euros or dollars.

German Finance Minister Christian Lindner on Thursday slammed as attempted "blackmail" any insistence by Moscow to now be paid in rubles in the face of Western sanctions over the Ukraine war.

President Vladimir Putin had earlier warned "unfriendly" countries, including all EU members, that they would be cut off from Russian gas unless they opened an account in rubles to pay for deliveries.

Deputy German government spokesman Wolfgang Buechner said Friday Berlin had received the "decree" in writing and was evaluating it "to determine its specific impact".

An economy ministry spokeswoman told the same briefing that it was too soon to assess the effect of the new Russian policy but noted that it gives the Gazprom Bank, charged with implementing the policy, "10 days to explain the details of the procedure" for payment.

Germany and Austria activated their emergency plans to secure gas supplies on Wednesday, as concerns rose that Russia could stop deliveries.

Before Moscow began its war in Ukraine, a third of Germany's oil imports, 45% of its coal purchases and 55% of gas imports came from Russia.

Economy Minister Robert Habeck said last week that it would likely take until mid-2024 for Europe's top economy to wean itself off Russian deliveries.