Greece can avoid gas supply problems indefinitely, even if Russia cuts off supplies, Energy Minister Kostas Skrekas said, adding that Greece's next payment to Russian supplier Gazprom should be made in April.

These measures will ensure supplies without any time constraints if there is enough gas on the world market, Skrekas told the Greek TV channel Skai.

Russian President Vladimir Putin signed a decree requiring foreign buyers to pay for Russian gas in rubles starting 1 April. In case of non-payment, the contracts will be terminated.

The order has raised concerns about gas supplies across Europe.

"The next payment will take place around 20 April, but we can't wait until then to see what happens," he said.

Under the emergency plan, he said, Greece, which uses gas mostly for power generation, will receive additional amounts of liquefied natural gas and convert four gas-fired power plants to diesel fuel. It may also increase its purchases of Azerbaijani gas.

"With all this, and with available gas volumes on world markets ... there will be no time constraints in terms of security of supply," he said.