Italian oil and gas company Eni SpA (E) expects to take a final investment decision toward the end of the year or start of 2013 on the South Stream natural gas pipeline project, Chief Executive Paolo Scaroni said Monday.

"All four partners are interested in South Stream," but still need to see all the details before making the decision, said Mr. Scaroni, on the sidelines of Eni's shareholder meeting in Rome.

South Stream--a joint project of OAO Gazprom (GAZP.RS), Eni, Germany's BASF SE (BAS.XE) and France's Electricite de France SA (EDF.FR) as minority partners--is envisioned to carry up to 63 billion cubic meters of Russian gas a year under the Black Sea to Europe, with first deliveries due in 2015.