MOSCOW: President Vladimir Putin warned on Wednesday that Russia may begin requiring advance payment for gas supplies unless Ukraine comes to the negotiating table over its unpaid energy bills.

Russia’s statecontrolled natural gas company “Gazprom will only send gas in the amounts that the Ukrainian side has paid for a month in advance” under the changed sale terms being contemplated, Putin said at a government meeting according to televised excerpts.

“They will receive as much as they have paid for,” he said. Russia says Ukraine now owes it $2.2 billion for natural gas supplies, and Gazprom last week demanded that Ukraine “take immediate measures” to settle the debt.