Russia says it has restricted gas supplies to Ukraine after a payment deadline passed, but that supplies to Europe should not be affected.
Sergei Kupriyanov, a spokesman for the state-controlled Russian energy giant Gazprom, said that -- since Ukraine had paid nothing toward its overdue gas bill within a set deadline on June 16 (9 a.m. Kyiv time) -- Moscow had no legal obligation to supply gas to Kyiv.
Kupriyanov said the talks in Kyiv, brokered by the European Union, failed just hours before Moscow's deadline.
Kupriyanov also said that Ukraine now has a duty to ensure that gas intended for European customers flows unimpeded.
Ukrainian Energy Minister Yuriy Prodan said on June 16 that Ukraine would both "guarantee the gas needs of Ukrainian consumers and ensure reliable gas transits to European countries."
Gazprom also said it has filed a lawsuit against Ukraine in a Stockholm arbitration court to recover $4.5 billion in debt.
Andriy Kobolev, the head of Ukraine's state company Naftohaz, confirmed that Russia has stopped delivering gas to Ukraine.
But Kobolev said Ukraine has enough reserves until December.
President Vladimir Putin had threatened to cut deliveries on June 16 unless Kyiv paid $1.95 billion within the stipulated deadline.
A statement from the European Commission says a plan envisioned by EU Energy Commissioner Gunther Oettinger had Kyiv prepared to pay $1 billion on June 16, with the remainder paid in installments by the end of 2014, but Russia rejected the offer.
The EU plan also would have seen Kyiv paying a "winter" price of $385 per 1,000 cubic meters for gas and a "summer" price of around $300.
Putin said $385 was his final offer.
Oettinger said he is aiming to arrange further talks in June and urged Moscow to reconsider a compromise offer, perhaps with small adjustments.
With reporting by Reuters, AP, and AFP