Shareholders of the South Stream subsidiary in Slovenia met with Gazprom officials in Moscow to reach a final investment decision on their leg of the gas pipeline for Europe.
"The final investment decision we adopted today is another important step to the South Stream project implementation, another stage of our work, aimed at securing natural gas supplies to Europe," Gazprom Chief Executive Officer Alexei Miller said in a statement.
Similar decisions were made by the Serbian and Hungarian governments.
This week, Bulgarian President Rosen Plevneliev said more transparency is needed in any deal with Gazprom. Bulgaria is considered a possible site for a European pipeline rival, Nabucco, which would carry natural gas from Azerbaijan.
Nevertheless, The Moscow Times reported Miller said he was confident that construction on the South Stream pipeline could begin at some point yet this year.
Gazprom aims to diversify its gas export routes to Europe through South Stream and its Nord Stream counterpart, which is already delivering gas through a Baltic Sea route.
South Stream is a twin network that would carry about 2.2 trillion cubic feet of gas per year when it goes into service by 2015.