OAO Gazprom, the world's biggest natural-gas producer, and Eni SpA may build a pipeline from Russia to the European Union.
This will bypass neighbors that have threatened to block supplies on existing routes, Bloomberg News reported.
The 900-kilometer South Stream pipeline could go under the Black Sea to Bulgaria and then split in two, Eni Chief Executive Officer Paolo Scaroni told reporters in Rome on Saturday. The project will now go through feasibility studies, and construction may start as early as next year, he said.
It will carry gas equal to as much as a third of German demand.
State-controlled Gazprom, seeking to bolster European sales and cut transit risks, has announced three new pipeline projects in 12 months. Neighbors including Ukraine and Belarus are used as transit countries for Russian gas sales to EU nations and both have threatened to block supplies because of pricing disputes.
"Gas is a political commodity nowadays; economically speaking, this project is not really justifiable," Vladimir Matias, managing partner of Asset Capital Partners, said on Saturday by phone from Vienna.
The new pipeline will provide a direct route into Italy and Austria and mirrors Gazprom's project with E.ON AG and BASF AG to build the Nord Stream pipeline to Germany.
South Stream will avoid the need to send gas through Ukraine and Belarus, while Nord Stream bypasses the Baltic states, which often have tense political relations with Russia.
Gazprom, based in Moscow, already supplies a quarter of Europe's gas needs. The company's profitability depends on exports since state-set gas prices in Russia are about a fifth of those in Europe.
Russia is seeking to regain control of energy assets and has pressured foreign investors into relinquishing their projects in the country. Royal Dutch Shell Plc ceded control of its US$22 billion Sakhalin-2 project to Gazprom in December, while a unit of BP Plc on Friday announced the sale of its 63 percent stake in a Siberian gas deposit to Gazprom.
For Eni, Europe's fourth-largest oil company, the pipeline would secure gas supplies for Europe's third-largest gas market behind the United Kingdom and Germany.
Italy buys 86 percent of its gas abroad, mainly from Algeria and Russia. The new pipeline may carry as much as 30 billion cubic meters of gas a year.