Within the next few weeks, the European Union will release the findings of its antitrust investigation, according to EU energy chief Maros Sefcovic. Europe has accused Gazprom of using its dominant position to manipulate prices and hinder the free flow of gas across the continent.

The EU has been investigating Russia's state-controlled Gazprom's pricing practices for over two years and if it decides to bring forward charges, a long legal battle is likely to follow.

 Any damaging findings against Gazprom could further worsen the Russia-EU relationship, already fractured over the conflict in eastern Ukraine.

President Vladimir Putin has warned this week that Gazprom could turn off the taps again. A new dispute could have a knock-on effect on Europe. About a third of the EU's natural gas comes from Russia and 15% flows directly through Ukraine.

"Europe is nervous of Putin's reaction and the possibility that he will act on a threat to reduce supplies," said David Clark from the Russia Foundation.