Europe's flagship project to bolster its energy security by building a major gas pipeline to the Caspian that skirts Russia is near collapse, analysts say, with a newly confident Turkey playing a key role.
Recent developments, including decisions by Ankara, have undercut the viability of the Nabucco pipeline, a project to ship more than 30 billion cubic meters of gas per year from the Caspian and beyond to Europe.
Repeated disputes between Russia and Ukraine over transit tariffs that led to supply cuts pushed the EU in 2009 to launch its Southern Gas Corridor initiative, of which Nabucco is the biggest project, to reduce its dependence on Russian gas supplies.
But in December, Turkey gave Russia the green light for its South Stream project to run through its Black Sea waters, with construction of the 63 billion cubic metres (bcm) per year pipeline to start by the end of this year.
"The Nabucco project was in a coma long before the South Stream agreement," said Necdet Pamir, a former deputy director of Turkey's TPAO oil company.
"But nobody dares to say Nabucco is already dead," he told AFP.
Nabucco was to run some 3,900 kilometres (2,400 miles) across Turkey then up through Bulgaria, Romania and Hungary to reach Austria where it would link up with a major distribution network.
Turkey also signed in December a deal with Azerbaijan to build the Trans-Anatolia Pipeline (TANAP) to carry 10 bcm per year of Azeri gas to European markets, plus 6 bcm for itself, casting further doubt on Nabucco which is having difficulty getting commitments of gas supplies.
Publicly, officials say Turkey, one of six partners in Nabucco, still supports the pipeline.
"We continue our efforts for this project to come true," Energy Minister Taner Yildiz said recently.
However, analysts believe Ankara is not wedded to the project.
"Turkey was not completely onboard on Nabucco," said Andrew Neff, senior energy analyst at IHS Global Insight, adding: "Turkey sees itself as a power arbitrator."
Ross Wilson, a former US Ambassador to Turkey and now director of the Dinu Patriciu Eurasia Center at the Atlantic Council in the United States, noted that approving South Stream may have improved Ankara's position as jostling continues over a final project.
"None of the recent developments regarding South Stream undermine or threaten in any way the Southern gas corridor -- recognising that this corridor may be Nabucco, ITGI, TAP or the new Southeast Europe line," he said.
It "may increase Turkey's leverage in the end-game negotiations over the coming months to finalise the Southern Gas Corridor pipeline, sales purchase agreements and the like," Wilson told AFP.
Two of the other competing pipelines are more modest projects to ship gas from Turkey across Greece to Italy -- the Interconnector Turkey-Greece-Italy (ITGI) and the Trans-Adriatic Pipeline (TAP) -- and both have said they are willing to cooperate with TANAP which would be able to provide them with sufficient supplies.
"Nabucco has been an incomplete project since the very beginning," said Mete Goknel, former director of Turkey's state-owned pipeline company, Botas, which is one of the Nabucco consortium partners.
"Who will ship the gas through the pipeline?"
Central Asia is Moscow's backyard and Russia's Gazprom has most supply tied up, while sourcing from Iraq's northern Kurdistan region is fraught given the political frictions with the central government in Baghdad.
The EU's dispute with Tehran over its nuclear programme takes Iran off the list of potential suppliers while unrest in Syria also currently rules it out.
Elnur Soltanov, Director of the Caspian Center for Energy and Environment at the Azerbaijani Diplomatic Academy, said recently that the Southeast Europe Pipeline (SEEP) promoted by British energy giant BP provides the best solution.
Like Nabucco, the pipeline would head up to Austria to serve more lucrative European markets, but at less cost due to its lower initial capacity and use of existing infrastructure.
The EU could present the pipeline as a short-term Nabucco, while its lower capacity would unlikely provoke Russia into a dispute, according to Soltanov.
"In the imperfect world of gas pipelines, SEEP represents the best of possible options for all parties involved," he wrote in a paper for Italy's International Affairs Institute, calling the the pipeline a "Nabucco Junior."
Analysts point out that even with a major pipeline like Nabucco that Europe's growing need for gas means that it won't be able to significantly reduce its dependence on Russia.
BP forecasts use of gas for power production in industrialised European countries will jump from around 40 percent currently to 60 percent in 2030, with Europe's import requirements likely to double by 2030 as a result.
Imports accounted for 444 bcm of the 553 bcm of gas the 27 EU member states used 2010, according to Eurostat.