Russia has given "hostile" countries a March 31 deadline to begin payments for natural gas imports in rubles. The new currency-switch rule will affect countries that imposed economic sanctions on the nation and froze its foreign currency reserves. This particularly concerns some EU countries that rely heavily on Russian energy supplies.

What will happen after March 31?
Russia says Europe will not get free gas if countries refuse to pay in rubles. "We are not going to supply gas for free, this is clear," Kremlin spokesman Dmitry Peskov said on Tuesday. When asked whether gas would be turned off for non-payers, Peskov replied: "No payment, no gas." He added, however, that Russia is yet to make a final decision on how to respond should European countries refuse to pay in the Russian currency.

How much does Europe depend on Russian gas?
Europe depends heavily on Russian gas for heating and power generation. Russian gas accounts for some 40% of Europe's total consumption. The EU's gas imports from Russia this year stood between €200 million and €800 million a day.