Russia has also yet to secure approval for the pipeline's construction from Bulgaria, which is looking negotiate lower gas prices as part of the project.
Bulgaria's Prime Minister, Boiko Borisov , said Tuesday that he expects the final decision on Thursday when Bulgaria and Russia are due to sign an agreement on Russian natural gas supplies. Borisov said that the pricing and terms of the gas deal are crucial for his country and that he favored a short-term gas supply contract.
"I am convinced that in the next three or four years we will have a lot of gas from the Black Sea, so we should avoid contracts for over six years," Borisov told reporters.
Gazprom's stock was down 1.6 percent Tuesday afternoon at the MICEX stock exchange, in line with the market.
Veselin Toshkov contributed to this report from Sofia, Bulgaria.