Bulgaria and Russia's gas giant Gazprom have proceeded to the selection of a feasibility study contractor for the Bulgarian segment of the South Stream pipeline, Gazprom's press service said on Friday.

Bulgaria gave the final agreement to prepare the South Stream assessment on October 22.

The documents required for participation in the open selection procedure are published on the website of the Bulgarian Energy Holding.

"We are confident that the national feasibility study of the project will be accomplished in the shortest amount of time, and as early as the first half of 2011 we will be able to make a decision on the optimization of the pipeline's route in Europe with a view on all the possible variants," Gazpom CEO Alexei Miller said in late October.

Russia has been exporting natural gas to Bulgaria since 1974. The volume of deliveries reached 2.64 billion cubic meters in 2009. Gazprom implements transit gas deliveries to Turkey, Greece and Macedonia through Bulgarian territory.

A transit contract between Gazprom Export and Bulgargaz company was extended from 2010 to 2030 in 2006.

The South Stream project, in which Russia, Bulgaria and Greece are partners, stipulates the construction of a 300-kilometer pipeline from Burgas on the Bulgarian Black Sea coast to Alexandroupolis on the Greek Aegean Sea coast. The pipeline, which is considered a rival to the EU-backed Nabucco, is scheduled to be launched in December 2015.

Intergovernmental agreements have been signed between Bulgaria, Serbia, Greece, Hungary, Slovenia, Croatia and Austria for the implementation of the section of the pipeline that will run over land.

The onshore part of the South Stream pipeline will pass through the Serbian town of Dimitrovgrad, 65 kilometers from the Bulgarian capital of Sofia.