By Alberto Sisto
ROME, May 7 (Reuters) - A dispute has erupted between Italian oil major Eni SpA and Russian state-controlled Gazprom over the role Eni will play in the South Stream gas pipeline, an Italian government source said on Thursday.
The Gazprom-led project aims to bring Russian, Caspian and Central Asian gas to Europe and is a rival to the European Union-backed Nabucco pipeline, which aims to reduce European reliance on Russia for its energy supplies.
Eni and Gazprom are 50 percent partners in the company which is conducting feasibility studies for the pipeline, but the Italian oil and gas producer's final role in the pipeline has not been defined.
The government source said Eni wants to be able to market gas from the pipeline in the countries the pipeline will pass through but that Gazprom was only offering the right to bring gas into Italy and a role in managing the pipeline.
"The Italian group wants to enter into the second phase of the project, that of selling the gas in the countries the pipeline will pass through... the Russians are putting up opposition, the talks are, however, still fluid," the source said.
Eni did not want to comment. A Gazprom spokesman declined immediate comment.
The Italian Prime Minister Silvio Berlusconi and his Russian counterpart Vladimir Putin are slated to meet at Sochi in Russia on May 15.
A previous meeting in April, when a statement on South Stream was expected, had been cancelled because of the Italian earthquake in Abruzzo.
The disagreement is the latest setback for the project, which had appeared to be speeding ahead of Nabucco, following Nabucco's difficulties in securing gas supplies.
On Wednesday, a source familiar with the situation said plans for Russia and the transit countries to sign an agreement on South Stream next week in Sochi were in doubt after the parties failed to agree on terms.
However, Serbian state gas company Srbijagas will sign a deal with Russia's Gazprom on May 15 on Serbia's participation in the South Stream gas pipeline, a spokesperson with Serbia's Energy Ministry said on Thursday.
No one from the Slovenian Ministry of Economy, which is in charge of the South Stream pipeline in Slovakia, will attend a signing ceremony in Sochi next week, an official said.
Eni and Gazprom have signed a series of Memoranda of Understanding on the development of the South Stream project since 2007.
South Stream will pass under the Black Sea and through Bulgaria, Serbia and Slovenia to Austria.
(Additional reporting by Tom Bergin in London; writing by Stephen Jewkes and Tom Bergin; editing by Simon Jessop)