It is "highly likely" that Russia will demand early repayment of $3 billion in debt owed by Ukraine, Russia's RIA Novosti agency reported on Saturday, citing an anonymous government source.
The source told the agency that Ukraine was in violation of a "whole series" of conditions for Russia's loan.
"In these circumstances it is highly likely that Russia will be forced in the near future to demand from Ukraine the early repayment of the $3 billion debt," the source was quoted as saying.
The comments appear to contradict remarks in November by President Vladimir Putin, who told German media that Russia did not intend to demand early repayment of Ukraine's debt as this would cause a financial collapse.
The finance ministry did not answer calls for comment on Saturday.
Russia lent the money in December 2013 by buying Ukrainian Eurobonds, before the overthrow of Ukraine's pro-Moscow President Viktor Yanukovich in February.
The terms included a condition that Ukraine's total state debt should not exceed 60 percent of its annual gross domestic product, a threshold which appears to have been crossed, Russian Finance Minister Anton Siluanov told Reuters in September.