Ukraine has collected 15 billion cubic meters of gas in underground storage as of September 14, part of its plan to store 18-19 bcm for winter by mid-October, gas transport company Ukrtransgaz said on Monday.
Kiev is pumping about 49 million cubic meters of gas into its reserves daily, it said in a statement, Reuters reported.
Ukraine uses gas from underground storage to safeguard supply in winter as well as to ensure there are no disruptions to Russian transit across the country to Europe.
The European Union receives about 40% of its Russian gas imports via Ukraine.
Kiev has said it needs at least $1 billion to buy enough gas for the winter season. Last week, the chief executive of Russia's Gazprom, Alexei Miller, said the EU might provide Kiev with $500 million for gas purchases of about 2 bcm.
Ukraine hopes to receive the remaining $500 million from the European Bank for Reconstruction and Development and from the International Finance Corporation.
Moscow and Kiev agreed last year on a "winter package" for supplies, with a price discount of $100 per thousand cubic meters and advance payments. That agreement expired on July 1 and has yet to be replaced.
Economic dealings between the two powers are complicated by a conflict between Ukrainian government troops and separatists in Ukraine's industrialized east in which up to 8,000 have been killed. Moscow denies Ukrainian and Western charges that its troops are directly supporting the separatists.
