Belarus has threatened to cut the supply of electricity via its territory to the Russian enclave of Kaliningrad.
The Belarus state power firm Belenergo said Russia was delivering electricity to the enclave in the absence of an agreement on transit fees.
"This compels the Belarusian side to think of cutting the unauthorised commercial transit of electricity," the Belenergo statement said on Monday.
A dispute over Russian oil supplies to Belarus has not yet been resolved.
Russian oil is still being supplied to Belarus, both for transit and processing, the Belarus oil concern Belneftekhim said.
But the two former Soviet republics have failed to sign a new agreement on Russian oil deliveries for 2010. It was supposed to be signed by the end of 2009.
"We are continuing uninterrupted transit to Western European customers," said Russian Deputy Prime Minister Igor Sechin, quoted by Interfax news agency.
Russian Prime Minister Vladimir Putin said he hoped a deal with Belarus on oil supplies would be clinched soon.
The dispute centres on the preferential tariff that Belarus has been paying since 2007 for Russian oil. It has been selling on Russian crude or refined oil at world prices.
Russia says it is prepared to sell oil to Belarus duty-free for domestic consumption but wants to charge the tariff for oil that Belarus exports.
In 2007 a similar dispute with Belarus over oil tariffs disrupted Russian oil exports via the Druzhba pipeline to Poland and Germany.