Putin's order last week to charge "unfriendly" countries in roubles for Russian gas has boosted the currency after it fell to all-time lows when the West imposed sweeping sanctions against Moscow over its military operation in Ukraine, which also sent European gas prices higher.

The move has drawn strong criticism from European countries, which pay for Russian gas mostly in euros and say Russia is not entitled to redraw contracts, with the G7 nations rejecting Moscow's demands this week.

"I believe we don't have to change the law, it's all stipulated there... The foreign currency will be exchanged at a market rate, which will be set at the Moscow Exchange," said Anatoly Aksakov, head of the financial committee in Russia's lower house of parliament, RIA news agency reported.

"They can buy it on forex, wherever. They can buy the roubles wherever," Aksakov said.

The Russian central bank, the government and Kremlin-controlled energy company Gazprom, which accounts for 40% of European gas imports, have been asked to present their proposals for rouble gas payments to Putin by March 31.

(Reporting by Reuters; Editing by Conor Humphries)