Europe and Russia will both lose heavily if President Vladimir Putin follows through on his threat to cut gas supplies to countries he judges "unfriendly" unless they pay in rubles.

Even at the height of the Cold War, Moscow never cut gas to Europe, but on Thursday, Putin signed a decree ordering foreign buyers to pay in rubles instead of euros from April 1 or face going without Russian supplies.

European capitals rejected the ultimatum and on Friday, Kremlin spokesman Dmitry Peskov said it would not affect settlements until later this month.