MOSCOW (Reuters) – Russian gas export monopoly Gazprom demanded Ukraine pay an overdue gas bill urgently on Tuesday, raising fears of a new “gas war” and increasing pressure on Kiev as it tries to build ties with Europe. Prime Minister Dmitry Medvedev described the payment problems as critical, ahead of Kiev’s signing next month of agreements with the European Union which would mark a historic shift away from former imperial master Moscow. Using language that harked back to earlier spats in which Moscow cut off gas to Ukraine, hitting onward deliveries to Europe, Medvedev told Gazprom ( GAZP.MM ) CEO Alexei Miller Kiev had not taken the payments seriously enough in recent talks. “The (problems) exist and they are absolutely critical,” he said at a government meeting. Miller said Ukraine had been given until October 1 to pay for natural gas deliveries in August, but no payment had yet […]