The shareholders in the Russian-sponsored South Stream gas pipeline project for carrying natural gas to Europe have agreed to build the northern leg to Austria before starting work on the southern leg to Italy, announced Paolo Scaroni, head of Italian energy company Eni

"This question is in the competence of [Russian gas giant Gazprom] and the transit countries, but we have come to agreement that the leg to Italy's south will be made after construction of the first onshore leg to Austria is completed," Scaroni told reporters, as cited by RIA Novosti.

The South Stream pipeline is intended to transport up to 63 billion cubic meters of Russian natural gas to Central and Southern Europe annually, diversifying Russian gas routes away from transit countries such as Ukraine.

The pipe will go from Russia to Bulgaria via the Black Sea; in Bulgaria it will split in two – with the northern leg going through Serbia, Croatia, Hungary, and Slovenia to Austria and Northern Italy, and the southern leg going through Greece to Southern Italy.

The construction of the South Stream gas pipeline will begin in December 2012, Russian Prime Minister Vladimir Putin announced on Thursday. Russia plans to start using the South Stream pipeline in 2015.

The pipeline's core shareholders include Gazprom with 50%, Italy's Eni with 20% and Germany's Wintershall Holding and France's EDF with 15% each.

"The construction of South Stream's offshore section will begin in December," Putin said during his meeting with at a meeting with Alexei Miller, head of Russia's Gazprom energy giant, while Miller announced that the pipeline would be launched in December 2015.

Gazprom has already established national joint ventures with companies from Austria, Bulgaria, Croatia, Slovenia, Greece, Hungary and Serbia to manage the onshore section of the South Stream pipeline.

Bulgaria recently committed itself to speeding up the construction of the Russian-sponsored pipeline on its territory, since on January 1, 2013, the EU is introducing new requirements for the access to energy networks.