"An environmental impact assessment was successfully finished ... spatial planning procedures aligned with the [Serbian] national law are nearing completion," Gazprom said in a statement Sunday.
Alexei Miller, chairman of Gazprom, met with Dusan Bajatovic, director general of Serbia's state-owned Srbijagas, at the Russian resort city of Sochi, host to the just-completed 2014 Winter Olympics.
Their talks focused on Serbia's onshore section of pipeline.
Construction on the Serbian section of South Stream began in late 2013.
The pipeline is meant to add diversity to Russia's export routes through Europe. A contractual dispute between Gazprom and its counterparts in Ukraine, which hosts most of Russia's gas for Europe, adds a layer of risk to conventional routes.
Gazprom said it plans to commission parts of South Stream before the end of 2015. It's designed to have an annual capacity of 2.2 trillion cubic feet.