South Stream Slovenia LLC, set up on parity basis, was registered on September 5, Gazprom said in a statement after a working meeting in Moscow between officials from the two partner companies.
The founding assembly of the joint venture's shareholders is planned to take place in early October in Ljubljana.
Gazprom said earlier South Stream Slovenia will be in charge of activities related to spatial planning, environmental impact assessment and drawing up the basic design of the Slovenian pipeline section.
The South Stream pipeline, a joint project of Gazprom and Italy's Eni, is expected to carry 63 billion cubic metres of Russian natural gas per year under the Black Sea to the Bulgarian coast. Slovenia, Bulgaria, Serbia, Croatia, Hungary and Greece are partners in the onshore section of the pipeline.