MOSCOW (Reuters) – Ukraine needs a total of 18.5 billion cubic meters of gas in storage to avoid problems in winter, double what it has now, Gazprom (GAZP.MM) Deputy Chief Executive Vitaly Markelov said on Tuesday. Moscow and Kiev are on the cusp of another gas war after Kiev has refused to pay at higher levels demanded by Gazprom. The Russian company is now asking for prepayment for June and says it will only provide gas that is paid for. “According to our colleagues (in Ukraine), 9 bcm is in storage. To pass through autumn and winter periods normally, we estimate that (Ukraine) needs around 18.5 bcm (in total),” Markelov told a news conference. “So around 9 bcm more is needed.” Ukraine wants to change the conditions of a 2009 contract that locked Kiev into buying a set volume, whether it needs it or not, at $485 per 1,000 […]