Belarus has threatened to suspend Russian oil and gas deliveries to Europe unless Russia pays what Minsk says is a $32 million debt in gas transit fees.
Interfax news agency today quoted Belarusian President Alyaksandr Lukashenka as saying the suspension would be effective within 24 hours.
Russian energy giant Gazprom denies owing anything to Belarus.
The Belarusian gas pipeline operator Beltransgaz confirmed on June 24 that it had received a transit payment from Gazprom. But the sum paid for the transit fees was given as $228 million; Minsk had demanded $260 million.
The spat comes just a day after Minsk resumed gas supplies to neighboring EU countries after a partial suspension.
Russia triggered the dispute last week when it said Belarus owed it around $200 million for gas deliveries and started to reduce flows.
Gazprom resumed supplies to Belarus on June 24 after Minsk paid the bill.
About 20 percent of Russian gas exported to Europe travels through Belarus.