REUTERS Natural gas reserves in Ukraine&#39;s underground storage facilities (USFs) have increased by 2.18 times, or by 8.75 billion cubic meters (bcm), to 16.19 bcm since April 9, when Ukraine started building up its gas stocks. Some 1.67 bcm of gas was injected into the USFs on September 1-29, 2018, according to the state-run gas transport system operator Ukrtransgaz. Natural gas reserves in Ukraine&#39;s USFs as of September 29, 2018, were estimated at 16.19 bcm, which was 1%, or 169.5 million cubic meters (mcm),&nbsp;down from 16.35 bcm reported as of September 29, 2017. Read alsoNaftogaz sees over $110 mln in losses over Gazprom&#39;s refusal to comply with arbitration award Ukrainian gas imports on September 1-29, 2018, totaled 1.15 bcm, including 718.6 mcm via Slovakia, 407.1 mcm via Hungary, and 19.7 mcm via Poland. Domestic gas output over the period under review stood at 1.67 bcm, while gas transit shipments totaled 6.99 bcm, it said. The country&#39;s USFs were filled by 52.3% as of September 29. As UNIAN reported earlier, Ukraine entered 2018 with 14.7 bcm of gas in its USFs, which was the largest gas stock as of the beginning of the year in the past five years.