The trend demonstrates Russia's resolve not to cut output despite calls from OPEC to independent producers to curb production to support falling prices.

Russian Economy Minister Alexei Ulyukayev put it more bluntly, telling reporters in Brussels that blocking Nord Stream-2 would be "a shot in the foot" especially for Gazprom's European clients.

A spokesman for the US oil and gas producer confirmed it had sold its 50 per cent stake in the venture, which is focused on the far north-west of Russia. Rosneft, the Russian state oil company, also sold its stake in the asset last week, in a deal that valued the business at about $150m-$200m, according to one person familiar with the matter.

Gazprom and some utilities say Nord Stream-2 is the most pragmatic solution to shoring up Europe's energy security. The European Commission has said it is assessing its legality.

Donald Tusk, president of the European Council, became the latest senior politician to criticise plans for a new pipeline bringing Russian gas to Germany, saying it would undermine the EU’s goal of reducing energy dependence on Moscow.

The deal, which could be worth around $1 billion based on the valuation of a recent stake purchase, is expected to take final shape during Prime Minister Narendra Modi's visit to Moscow next week for summit talks with President Vladimir Putin, said the sources with direct knowledge of the situation.

In theory, the European Union is pursuing a single energy market, based on the needs of all 28 EU nations. It is also meant to be united against Russia as it seeks to defend the interests of Ukraine following Moscow's seizure of Crimea in March last year.

Nord Stream-2 is still supposed to meet a hypothetical rise of EU gas demand, and also to deal with the abandonment of other projects, like the Nabucco project, which was largely abandoned in 2012, the South Stream project abandoned in December 2014, as well as the ill-fated Turkish Stream project, held hostage in the Russian-Turkish war of words that has followed the shooting down of a Russian warplane by the Turkish Airforce.

The Nord Stream II pipeline would stretch 1,200 kilometers across the Baltic Sea, from Vyborg on the Russian coast to Griefswald, Germany. Once completed, it would have the capacity to transport 27.5 billion cubic meters of gas directly to Germany, circumventing Ukraine and the Central and Eastern European states. Russia’s Gazprom would own 50% of the project, and France’s Engie, Austria’s OMV, Royal Dutch Shell, and Germany’s BASF and E.ON each would own a 10% share.

The additional volumes are roughly what Gazprom has been piping to the EU through Ukraine, raising concerns that the new route would allow Russia to strip Kiev of much of its remaining economic leverage and an important source of income.