Serbia has signed a 2.1 billion euro ($2.9 billion) contract with a Gazprom subsidiary to construct the South Stream pipeline across its territory.
The contract between South Stream Serbia and Tsentrgaz was signed in Belgrade late on July 8.
Gazprom earlier said its subsidiary had won a tender for the construction of the pipeline in Serbia.
The contract was signed as Serbian Prime Minister Aleksandar Vucic held talks with Russian President Vladimir Putin in Moscow on July 8.
Gas should start flowing through the Serbian section of the pipeline by the end of 2016.
South Stream is planned to carry Russian natural gas across the Black Sea and the Balkans to countries in southern and central Europe.
The project stalled when the European Commission expressed concern that Russia's bilateral agreements with EU-member transit countries violate its competition rules.
Based on reporting by B92 and RT