Two days of talks between Russia and Belarus on resolving a dispute over oil have ended with no result, according to both sides.
The disagreement has raised the prospect of disruptions to the European Union during an especially cold winter.
Russia briefly cut oil supplies this month to Belarusian refineries after failing to agree oil-price terms for this year.
A Belarusian source close to the talks in Moscow says the negotiations had stalled, and that his country's delegation was heading home to Minsk.
A Russian Energy Ministry spokeswoman, however, says the two sides are closer to an agreement and that the delegations are in constant contact.
The dispute centers on how much export duty Belarus should pay to Russia for its oil, which is then refined and exported to the West.