President Vladimir Putin talked tougher Thursday, saying Russia will start accepting ruble payments for its gas supplies from ``unfriendly countries`` starting Friday and contracts will be stopped if buyers don't sign up to the new conditions.

He says to buy gas, customers ``would have to open ruble accounts in Russian banks.``

The decree Putin signed and published by state news agency RIA Novosti says a designated bank will open two accounts for each buyer, one in foreign currency and one in rubles. The buyers will pay in foreign currency and authorize the bank to sell that currency for rubles, which are placed in the second account, where the gas is formally purchased.