Russia said Kiev missed a deadline for a $1.95 billion debt payment and it would now only get gas it has paid for in advance. It insisted Ukraine must also ensure that it lets Russian gas flow through international pipelines to Moscow's clients in the European Union.

Kiev and Moscow blamed each other for the failure to agree overnight on the price of future gas deliveries and refused to abandon well established positions: Russia offering a discount and Ukraine rejecting that as a tool for political manipulation.

The talks are bound up with the worst crisis between Russia and Ukraine since the Soviet Union collapsed - a crisis that has brought Western sanctions on Moscow, the Russian annexation of Crimea and Cold War-style sabre-rattling along the borders.

Western-backed Ukrainian President Petro Poroshenko, elected last month to replace the ousted president in February, said on Monday he wanted troops to regain full control of the border with Russia this week.

Sources at Gazprom said supplies to Ukraine had been reduced as soon as the deadline passed and Ukrainian Energy Minister Yuri Prodan said the country was receiving no gas.

Ukraine has at least 12 billion cubic meters of gas in storage, enough to meet its and the EU's needs over the summer.

A long-term reduction of supply could hit EU consumers, which get about a third of their gas needs from Russia, around half of it through pipelines that cross Ukraine.

NJF/NJF