Image from фото eer.ru NJSC Naftogaz of Ukraine has commented on a new claim Russia&#39;s gas giant Gazprom has lodged to an international arbitration seeking to cancel its supply and transit contracts with Ukraine. "[Gazprom&#39;s] appealing the arbitration award does not suspend the contracts. Gazprom still owes us US$2.56 billion plus interest," Naftogaz&#39;s press service has said. Read alsoRussia&#39;s Gazprom failing to fulfill obligations under gas transit contract – Naftogaz envoy Gazprom announced on Friday, April 20, that talks with Naftogaz over the contracts had ended without concrete results and it had lodged a claim to a Stockholm arbitration court. The negotiation period for the supply contract expired on April 4 (30 days from the start of the dispute or disagreement) and on April 19 for the transit contract (45 days). Naftogaz&#39;s press service also noted that the contracts do not provide for their termination unilaterally. Both contracts – for the supply of gas and gas transit shipments – expire at the end of 2019. Naftogaz also recalled that the previous arbitration proceedings lasted more than three years. Last month Gazprom appealed against a previous Stockholm arbitration ruling, which obliged the Kremlin-controlled company to pay Naftogaz $2.65 billion following a long dispute between the companies over gas delivery. The court also obliged the Russian gas producer to supply up to 5 billion cubic meters of gas in 2018-2019 at prices that are equal to those of European gas hubs. After it had lost the court case, Gazprom said it would terminate its gas contracts with Ukraine and it officially notified Naftogaz late in March that it was not going to fulfill the arbitration ruling.