Moscow said it would set up a formal joint venture in Bulgaria by Nov. 15 to draft a feasibility study for the South Stream natural gas pipeline.
The Kremlin said Russian Prime Minister Vladimir Putin secured the deal with his Bulgarian counterpart Boyko Borisov during a telephone conversation.
"Putin and Borisov agreed that a Russian-Bulgarian joint venture to develop a feasibility study for the Bulgarian section of the pipeline will be created before Nov. 15 of this year," Russia's state-run news agency RIA Novosti quoted the Kremlin as saying.
Borisov in early October said he was coordinating his country's position with Turkish and Georgian interests in the planned Nabucco pipeline. He noted the European Union had set aside roughly $275 million for the multibillion-dollar project. Sofia, he said, needed another $80 million to build connections to the pipeline.
He said the country's finance minister wouldn't sanction a loan to build a 47-mile pipeline to connect to Turkey because of the consequences for the Bulgarian economy.
Turkey has plans to host a section of Nabucco in its territory, while South Stream would run through Turkish waters.