Ukraine's state-owned energy company, Naftohaz, says it has paid its $1.5-billion natural gas debt to Russia, avoiding a possible cut off of supplies.
Ukrainian gas official Valentin Zemliansky says the payment is for gas deliveries in November and December.
Russia's state-run gas company, Gazprom, says it has not yet received payment. Russia also says Ukraine owes more than $2 billion.
Gazprom said earlier it has formed an operations center to implement a cut-off of supplies if Ukraine fails to pay its outstanding debts before New Year's Day.
Gazprom also wants to more than double its charges for gas to Ukraine to $418 per 1,000 cubic meters of gas for next year - roughly the same as what other European countries pay.
A cut-off of supplies to Ukraine could disrupt the onward delivery of gas to western Europe during the coldest time of the year.
Gazprom supplies European Union states with about one-quarter of their natural gas needs and delivers most of that gas through Ukraine.
Ukraine has struggled to pay its debts this year because of the global financial crisis. Kyiv recently sought $14 billion in aid from the International Monetary Fund.
Gazprom is offering to forgive Ukraine's $2-billion debt if the amount is used to offset future Russian payments for transporting gas through Ukraine to Europe.
Russia briefly cut gas shipments to Ukraine in January 2006 in a previous pricing dispute that resulted in reduced gas deliveries to Europe.
Some information for this report was provided by AFP and Reuters.