The EU's executive body imposed binding obligations on Gazprom. It will face a fine of up to 10 percent of its annual global turnover, which amounted to around 91 billion euros in 2017, if it breaks these obligations.
"Today's decision removes obstacles created by Gazprom, which stand in the way of the free flow of gas in Central and Eastern Europe," EU Competition Commissioner Margrethe Vestager said in a press release on Thursday.
"Now Gazprom has to take positive steps to integrate gas markets in Central & Eastern Europe: To enable gas to flow freely at competitive prices. Helps consumers. This is the start of enforcing Gazprom obligations. Broken obligations can lead to fine of up to 10% of turnover," she tweeted.
Under the legally-binding commitments, Gazprom has to remove any restrictions placed on customers to re-sell gas across borders and to enable gas flows to and from parts of Central and Eastern Europe that are still isolated from other member states due to the lack of interconnectors, namely the Baltic states and Bulgaria, according to the press release.
"Gazprom customers are given an effective tool to make sure their gas price reflects the price level in competitive Western European gas markets, especially at liquid gas hubs," it said.
At Lithuania's initiative, the EC launched the probe into Gazprom's possible infringements in eight member states in 2012.
The EC said in April 2015 that the Russian gas giant might have set unfair gas prices and abused its dominant position.
Gazprom last year promised to enable free gas supply in the Baltic countries and ensure competitive prices, but the Lithuanian government demanded that it compensate for damages. Other countries in the region also called for tougher sanctions against the Russian supplier.