The European Union's executive hopes to broker a deal to resolve a stand-off in which Moscow has shut off gas deliveries to Ukraine over what it says are more than in $5 billion (3.09 billion pounds) unpaid bills.

After months of negotiations Russia and Ukraine seemed to be on the brink of a deal last week at talks in Berlin.

Russian Energy Minister Alexander Novak said earlier this week that negotiations would continue in Berlin on Thursday and Friday.

But contradicting Novak, a spokeswoman for the Russian energy ministry told Reuters in Moscow on Wednesday that no date had yet been agreed for more talks.

A European Commission spokeswoman said the EU executive was "looking into a possible date and place for the next trilateral meeting".

The Commission was reviewing comments received late on Tuesday from Russia and Ukraine, she said.

Energy Commissioner Guenther Oettinger, who is scheduled to leave office at the end of this month and take up a new Commission post, has been pressing hard for a deal before the peak demand winter season.

The European Union, which relies on Russia for roughly one third of its gas supplies, around 40 percent of which is shipped via Ukraine, is nervous about possible knock-on effects from the ongoing row.

Russian gas exporter Gazprom cut off Ukraine's gas in June citing unpaid bills and has said it expects Ukraine to pay off some of its debts before it resumes supply.

(Reporting by Barbara Lewis and Tom Koerkemeier in Brussels and Vladimir Soldatkin in Moscow; editing by Adrian Croft and Jason Neely)