
The Stockholm arbitration court, which has been working on the multi-faceted case, ordered Russian-owned Gazprom to pay $4.63 billion (3.79 billion euros) for "failure to deliver the agreed transit gas volumes", the Ukrainian gas operator Naftogaz said.
"Gazprom will have to make a net payment of $2.56 billion to Naftogaz," it added in its statement, following a a previous judgment against Naftogaz to pay around $2 billion to the Russian public giant.
Since the pro-Western authorities came to power in Ukraine in 2014, the two neighbours have been waging a furious legal battle over multi-billion-dollar claims Moscow and Kiev have against each over.
The Stockholm court's complex decisions are not public and their details are only partially revealed by each party. Gazprom had not responded on Wednesday evening to the new decision.
The latest finding deals with the transit of Russian gas through Ukrainian territory.
Ukrainian infrastructure minister Volodymyr Omelyan welcomed the decision, saying on Facebook it was a "victory in Stockholm", even though the payment ordered falls well below the amount claimed by Kiev of around $15 billion.
In December the court lowered the price Russia can claim for its gas, but also maintained the obligation for Kiev to buy gas from its neighbour, although in much smaller volumes.