REUTERS CEO of National Joint-Stock Company Naftogaz of Ukraine Andriy Kobolyev says natural gas stocks in Ukraine&#39;s underground storage facilities (USFs) have increased to 19 billion cubic meters (bcm) as of Sept 11, so Ukraine has to accumulate 1 bcm of gas before the start of the heating season. "We have exceeded the mark of 19 bcm [of gas] in our underground storage facilities. We are ahead of the plan," he wrote on Facebook on Wednesday, Sept 11. At the same time, the daily gas transit amounted to 247.9 million cubic meters (mcm), while gas imports from the EU states stood at 68.7 mcm, Kobolyev said, referring to the state-run gas transport system operator Ukrtransgaz. As UNIAN reported earlier, Ukraine on April 5 started the season of pumping natural gas into its underground storage facilities. It is planned to accumulate more than 20 bсm in the USFs before the start of the heating season in the middle of October. Read alsoNaftogaz reacts to European court ruling on OPAL gas pipeline By the start of the 2018-2019 heating season, Ukraine had accumulated 17.2 bcm of gas in its underground storage facilities, which was a record high natural gas stock over the past six years. Additional volumes of gas in storage facilities are required to smoothly pass the heating season if Russia completely halts the transit of gas via the territory of Ukraine. The current transit contract between Ukraine and Russia&#39;s Gazprom was signed in 2009 for a period of 10 years. Once it expires (from 2020), the Russian monopoly plans to minimize gas transit through the Ukrainian territory.