Russia's gas giant Gazprom on Wednesday confirmed receipt of part of the money Ukraine owes it for gas, but Kiev must now pay ahead for the gas to flow.
Ukraine's state-owned energy group Naftogaz said late Tuesday that Kiev has paid $1.45 billion, the first tranche of $3.1 billion of its gas debt.
"The banks told us that the amount Ukraine owes for last year is on their way," said Gazprom spokesman Sergei Kupriyanov.
Gazprom had cut gas deliveries to neighbouring Ukraine in June, leading to fears by European consumers that Ukraine may be forced to tap into the gas it transports westwards.
After several acrimonious rounds of talks the sides reached an agreement last week that Kiev must pay the full amount it owes before the end of the year and set a new price for Ukraine at $385 that will be valid through March 2015.
Deliveries will resume "as soon as prepayment arrives", Kupriyanov told AFP, confirming that gas would flow 48 hours after Gazprom receives the money.
Gazprom says Naftogaz owes it a total of $5.3 billion, and a Stockholm arbitration court is to decide on whether Ukraine must pay the $2.2 billion difference or not.