KIEV, Dec. 23 - Ukrainian state energy firm Naftogaz said on Tuesday it had transferred $1.65 billion to Russia's Gazprom - the second tranche of a debt repayment agreed under a deal that saw Moscow resume gas supplies to Ukraine earlier this month, Reuters reported.

In November, Moscow, Kiev and the European Union reached a deal under which Russia would restart flows to Ukraine over the winter in return for Ukraine paying $3.1 billion in two tranches by the end of the 2014.