Russian officials went to Brussels to trumpet South Stream. Geopolitical rows with transit-nation Ukraine led Europe and Russia to seek new sources and delivery routes for natural gas.
About 80 percent of all Russian gas supplies for Europe travel through Soviet-era pipelines in Ukraine.
Moscow is nearly finished building the Nord Stream gas pipeline through the Baltic Sea and is courting European partners for South Stream, which would travel through the Black Sea.
"Having united many European countries around itself, the South Stream project will not merely eliminate current deficiencies in the development of the region's gas infrastructure but will also contribute to further regional collaboration," said Alexei Miller, the chief executive of Gazprom, in his statement to European officials.
Europe, however, is eager to break the Russian grip on the regional energy sector through the so-called Southern Corridor, which includes the Nabucco natural gas pipeline.
Gunter Oettinger, the European commissioner for energy, said his bloc "clearly has preferences" for natural gas, adding South Stream is "not our top priority."
"We support some projects more than others, that is clear," he said. "In this regard, I reaffirm again what I have said many times before: the EU wants direct contacts with Caspian producers through new supply routes and pipelines."