Russia cut off gas to Ukraine on Monday in a dispute over unpaid bills that could disrupt supplies to the rest of Europe and set back hopes for peace between the former Soviet neighbours, according to The Associated Press.
After the weekend loss of 49 troops when pro-Russian rebels shot down a military transport plane, Ukraine's new president ordered his forces to retake full control of their border with Russia, the AP reported.
Russia said Kiev had missed a Monday morning deadline to repay $1.95 billion owed for previous purchases and announced Ukraine would now only get gas it has paid for in advance, according to the AP. At the same time, Moscow insisted that Ukraine must let Russian gas flow across the country through international pipelines to Russia's clients in the European Union, noting a temptation for Kiev to tap into those supplies in transit.
The gas talks are bound up with the worst crisis between Russia and Ukraine since the Soviet Union collapsed, the AP reported.
Western-backed Ukrainian President Petro Poroshenko, elected last month to replace the Kremlin-friendly leader ousted in February, said on Monday he wanted troops to regain full control of the border with Russia this week, according to the AP. He also announced there could be a ceasefire and efforts to come up with a peace plan.
"The ceasefire will be declared as soon as the border is secure," Poroshenko told his security chiefs, the AP reported. "Declaring a ceasefire while the border is open would be irresponsible."
Hopes of a lowering of tension had already been dented before the gas talks failed by the downing of the plane near the eastern frontier, an attack on Russia's embassy in Kiev and new accusations from NATO that Russia is arming the Ukrainian rebels, according to the AP.
"Thanks to the unconstructive position of the Ukrainian government, today a prepayment system was introduced," Alexei Miller, the chief executive of Russian state exporter Gazprom, told Prime Minister Dmitry Medvedev during a meeting at a government residence at Gorki, outside Moscow, the AP reported.
At a news conference, he said it would no longer be enough for Kiev to pay part of its debt for supply to resume, which would only happen once Ukraine paid off all the almost $4.5 billion and paid up-front for a month's deliveries, according to the AP.
Miller said Ukraine had "adopted a position that can only be called blackmail", adding: "They wanted an ultra-low price," the AP reported.