Russian President Dmitry Medvedev has said Moscow could impose sanctions against Ukraine if Kiev does not pay up its gas debt to the last rouble.
Russian news agencies reported his comments on Christmas Eve as Russian gas giant Gazprom renewed its threat to cut off gas supplies to Ukraine on 1 January, saying a contract dispute has reached a critical stage.
Gazprom said the dispute would not disrupt gas deliveries to Europe, which gets 42% of its supplies from Russia, mostly via pipelines across Ukraine.
The company said Ukraine owes it $1.67bn for gas and $450m in fines.
A similar row in 2006 led to gas shortages in several EU countries.
