Gazprom said Monday in a statement Miller met in Moscow with Ukraine's acting Deputy Prime Minister Yuri Boiko to discuss "the issues of operation in the winter period and repayment of the existing gas debt by [Ukraine's natural gas company] Naftogaz Ukrainy."
Russian President Vladimir Putin's office said Ukraine is already falling behind on its energy bills and owes Gazprom more than $3 billion, state news agency RIA Novosti reported.
Gazprom in 2009 cut gas supplies to Ukraine because of contractual disputes. That left downstream consumers in Europe in the cold for several weeks as most of their Russian gas runs through the Soviet-era transit system in Ukraine.
After Ukraine's November decision to suspend association talks with the European Union, Putin cut Ukraine's gas bill by more than 60 percent.