A pressure valve on a pipeline at the Bilche-Volytsko-Uherske underground gas storage facility, not far from the village of Bilche in the Lviv region of western Ukraine

Kiev has paid the first tranche of its debt to Russia's Gazprom, fulfilling the terms of a gas deal in order to get Moscow to resume deliveries to the former Soviet state, Ukraine's energy company Naftogaz said Tuesday.

The state-owned energy group "Naftogaz has transferred to Gazprom the first tranche of 1.45 billion dollars in debt", it said in a statement. Under the agreement, the full amount of $3.1 billion must be repaid by the end of the year in order to keep gas flowing in 2015.