Russia and Slovenia have signed an agreement on the South Stream gas pipeline project.

Russian Prime Minister Vladimir Putin and his Slovenian counterpart Borut Pahor attended the ceremony where the accord was signed by their respective energy ministers, Sergei Shmatko and Matej Lahovnik, on Saturday at Putin's residence at Novo-Ogarevo near Moscow.

The massive South Stream gas pipeline from Russia to Western Europe will pass through Slovenia, which is the latest European partner of the project.

Before Slovenia came on board, Russia had signed South Stream agreements with Bulgaria, Hungary, and Greece.

Analysts say that with the move, Moscow has dealt another blow to the rival Nabucco pipeline project, which is meant to reduce EU dependence on Russia for gas by allowing the European Union to acquire supplies from nations like Azerbaijan and Turkmenistan.

The 20-billion-euro (30-billion-dollar) pipeline should be completed by 2015 and will run under the Black Sea to Bulgaria, Serbia, and Hungary before branching out to Western Europe.

Its total capacity could reach 63 billion cubic meters (2.2 trillion cubic feet) a year.

South Stream is one of two major pipeline projects that Russia is developing, with the goal of consolidating its commanding position in supplies of gas to Europe. The other, Nord Stream, is to run under the Baltic Sea from Russia to Germany.

FTP/SS/HGL