Germany's Wintershall, a unit of BASF, is set to join Russia's South Stream pipeline that will carry gas under the Black Sea to Europe, a source close to energy giant Gazprom told Interfax on Friday.

The source, however, said that Gazprom, which leads the project together with Italy's ENI, is not considering reducing its stake.
Earlier on Friday, ENI's CEO, Paolo Scaroni, said in an interview with the Wall Street Journal that a German company would be joining South Stream in the next few days, which partners hope will help the pipeline gain favor with the European Union.

Gazprom could not be reached for comment.

France's EDF also holds a stake in the pipeline that will transport up to 63 billion cubic meters of gas to central and southern Europe. The cost is estimated at around $21.5 billion.

Wintershall has long been rumored to become South Stream's fourth stakeholder, with ENI saying last year the German company was considering joining.

South Stream is looking to gain more favor in the EU, which already supports the rival $10.8 billion Nabucco project that will sidestep Russia and Ukraine by piping gas directly from Central Asia to Europe under the Black Sea.