Russian, Ukrainian prime ministers uphold gas deal

Naftogaz said on Wednesday it had paid a second tranche of arrears of $178 million. Russian gas export monopoly Gazprom puts the total at $1.5 billion. (Writing by Dmitry Zhdannikov and Ron Popeski, editing by Anthony Barker) - MOSCOW, Feb 20 - The prime ministers of Russia and Ukraine said on Wednesday they would stick to gas deals reached by their presidents earlier this month, calming fears that Ukraine's premier could challenge the agreement.