Gazprom says Turkey has given permission for a gas pipeline to be built across its territories, giving the project a clear path from Russia to Europe.
The South Stream line will transport Russian gas to Europe under the Black Sea. It will now be able to bypass Ukraine.
Investors in the project are: Gazprom of Russia 50%, ENI of Italy 20%, EDF of France 15% and Wintershall of Germany 15%.
The BBC reports the full pipeline is expected to be completed by the end of 2015.