Nabucco is the most ambitious of the three natural gas pipelines outlined in the so-called Southern Corridor, a network of gas transit routes meant to break Russia's grip on the European natural gas sector.
Julian Lee, an analyst at the Center for Global Energy Studies, told online news service New Europe that Turkey's plans to move ahead with the alternate Trans-Anatolia gas pipeline through its territory likely spelled the end of Nabucco.
"I think that Nabucco in the way that it was originally envisaged as a pipeline running from Turkey's eastern border all the way to Europe … is probably over," he was quoted as saying. "I don't think that is going to happen."
Nabucco officials maintain their option is the best for Europe. The project is viewed as too costly, however, and so far lacks concrete supply agreements from countries such as gas-rich Azerbaijan.
Russia said its South Stream natural gas pipeline, viewed as a direct competitor to Nabucco, could start construction as early as December.