European Union Energy Commissioner Guenther Oettinger was joining the talks Saturday along with Ukrainian Prime Minister Arseniy Yatsenyuk and the heads of Ukraine's Naftogaz and Russia's Gazprom companies.
Talks broke off last week after Ukraine balked at Russia's latest price demand.
The dispute has been going on for months. Moscow has threatened to turn off the tap if Ukraine fails to settle its multibillion-dollar debt. Russia also says if the dispute is not solved by Monday it will start demanding payment in advance for gas deliveries from Ukraine.