Gazprom said Friday that Belarus was refusing to pay agreed prices for fuel supplies, with the country already owing $192 million for its gas this year.
The debt expanded by $55 million after Beltransgaz, the state pipeline operator half-owned by Gazprom, underpaid on Friday, Gazprom spokesman Sergei Kupriyanov said.
Beltransgaz spokesman Vladimir Chekov did not answer his office or mobile phones when called by Bloomberg.
Putin said in March that Belarus would receive $4.2 billion in Russian subsidies this year through below-market gas prices and tax-free oil deliveries. Gazprom also paid $625 million this year for 12.5 percent of Beltransgaz, whose pipelines carry about one-fifth of Russia's Europe-bound gas exports.
"Beltransgaz decided to pay for supplies not at the contract price, but at a price it determined by itself," Kupriyanov said. At the current rate, the debt may reach $500 million to $600 million this year, he said. "The unfolding situation concerns us greatly."
Belarussian Energy Ministry spokeswomen Lyudmila Zenkovich declined comment, Interfax reported.
The comments came as Prime Minister Vladimir Putin was meeting in St. Petersburg with counterparts from the Eurasian Economic Community, including Belarussian Prime Minister Sergei Sidorsky.
Gazprom will charge Belarus an average of $171.50 per 1,000 cubic meters of gas this year, Interfax reported on March 26, citing the state-run gas export monopoly.