Gazprom said progress was made during the meeting.

The comments by the EU competition authority came after Gazprom deputy chief executive Alexander Medvedev met EU antitrust chief Margrethe Vestager to discuss the case in Brussels.

"Our exchanges with Gazprom continue and, on this basis, Gazprom will first have to submit an improved commitments proposal. So, there is still some work ahead," a Commission spokesman said in an email.

The Russian state-controlled company is fighting allegations of overcharging customers and blocking East European rivals in contravention of EU rules. It denies the allegations.

Gazprom said it and the Commission had agreed to continue work on "seeking a mutually acceptable solution" in relation to the EU's investigation into the company's practices.

"We are satisfied about the outcome of today's meeting, which was conducted in a constructive atmosphere," Gazprom's Medvedev said in a statement.

The EU antitrust authority has said Gazprom's gas price formula, which is linked to the oil price, has led to consumers in Poland, Lithuania, Bulgaria, Estonia and Latvia paying excessive prices compared with Germany. Gazprom denies any wrongdoings.

Gazprom, which supplies a third of the EU's gas, is facing fines of up to 10 percent of its global turnover.

To meet EU requests, Gazprom offered to let clients renegotiate decades-long, oil-indexed contracts, with prices linked to benchmarks such as European gas market hubs and border prices, including in Germany.

Gazprom's concessions were market tested among rivals and customers. The proposals made during the "market test" were discussed during the Friday talks, Gazprom said.

(Reporting by Vladimir Soldatkin in MOSCOW and Foo Yun Chee in BRUSSELS; additional reporting by Alissa de Carbonnel; Editing by Jane Merriman and David Evans)

By Vladimir Soldatkin and Foo Yun Chee