Gazprom said Friday that it agreed to carry out a feasibility study of the Bulgarian segment of the planned South Stream pipeline.
The company signed the agreement with Bulgaria's energy holding and pledged to carry out the feasibility study quickly, it said in an e-mailed statement.
"In the first half of 2011, we will be able to make a decision about the optimal route of the pipeline in Europe, taking all the options into account," chief executive Alexei Miller said in the statement.
Gazprom plans to build the pipeline to supply Eastern, Central and Southern Europe, bypassing transit states such as Ukraine. The construction is planned to start in 2013, with the first gas deliveries at the end of 2015.
Romania signed an accord with Gazprom earlier this month about the possible construction of South Stream across its territory. Gazprom has not made a final decision on the route.