South Stream (Russian: Южный поток, romanized: Yuzhnyy potok; Bulgarian: Южен поток, romanized: Južen potok; Serbian: Јужни ток; Slovene: Južni tok; Hungarian: Déli Áramlat; Italian: Flusso Meridionale) is a canceled pipeline project to transport natural gas of the Russian Federation through the Black Sea to Bulgaria and through Serbia, Hungary and Slovenia further to Austria.

The project was found in non-compliance with the European Union's Third Energy Package legislation, which stipulates the separation of companies' generation and sale operations from their transmission networks.

[15][16] On the same day, Russia and Hungary agreed to set up an equally owned joint company to build and operate the Hungarian section.

[22][23] As per earlier 2008 agreement between two countries, on 17 November 2009, Russian Gazprom and Serbian Srbijagas created South Stream Serbia AG in Bern, Switzerland.

[25][26] On 19 June 2010, Gazprom, Eni, and Électricité de France published a joint press release confirming that EDF will join the project.

[29] However, on 16 September 2011, a shareholders' agreement was signed between Gazprom, Eni, Électricité de France and Wintershall to establish the new project company South Stream Transport AG for the Black Sea section of the pipeline.

[5][33][34][35] On 15 November 2012, shareholders of South Stream Transport AG signed the final investment decision on the offshore section.

[5] The ground-breaking ceremony marking start of construction of the Russian onshore facilities was held on 7 December 2012 at the Russkaya compressor station near Anapa.

[44] In April 2014, Russia filed a complaint at the World Trade Organization against the European Union's energy market laws that were enacted in 2009, claiming that they violate international rules.

[45] On 1 December 2014, during a state visit to Turkey, president Putin announced that Russia was withdrawing from the project, blaming international sanctions and lack of construction permits in the territory of the European Union.

[9] Along with additional supplied to Turkey, Russian gas, according to Putin, “will be retargeted to other regions of the world, which will be achieved, among other things, through the promotion and accelerated implementation of projects involving liquefied natural gas.” In 2015, the supply of Russian gas to Turkey will be raised by 3 billion cubic meters via the already operating Blue Stream pipeline.

[citation needed] In 2018, Bulgaria's president Rumen Radev proposed that the construction of the South Stream pipeline be resumed.

[37] The 931-kilometre (578 mi) long offshore section was to run from the Russkaya compressor station through the Black Sea to Galata near Varna, Bulgaria.

From Čenta the main pipeline would have continued in direction of Gospođinci while branch-off line would run to Republika Srpska in Bosnia and Herzegovina.

For the construction and operation of the offshore section of South Stream originally two companies were established, both in Zug in Switzerland with the share capital of 100,000 CHF.

[41] Gazprom owns 50% of shares of South Stream Transport AG, Eni 20%, and Électricité de France and Wintershall 15% both.

[4] Some experts like Alan Riley from London City University were claiming that the South Stream pipeline is a political project to counter Nabucco and to expand Russian presence in the region.

[79] CEO of Eni Paolo Scaroni proposed to merge Nabucco and South Stream projects to "reduce investments, operational costs and increase overall returns".

[21] Before stepping down from the premiership, Italian Prime Minister Romano Prodi received an offer from Gazprom to become the Chairman of South Stream AG.

"[85] In May 2014, it was disclosed that the contract for construction of the Bulgarian section was awarded to Stroytransgaz, a company controlled by Gennady Timchenko through his Volga Group.

Earlier Timchenko was included in the sanctions list in the wake of the Russian annexation of Crimea due to his close ties with President Putin.