The Bulgarian government announced Wednesday that it considered the planned Nabucco pipeline an object of national importance.
Reinhard Mitschek, managing director of Nabucco Gas Pipeline International GmbH, said the decision was a milestone for the project.
"We welcome this momentous decision by the Bulgarian government and its renewed commitment to the Nabucco pipeline project," he said in a statement.
Nabucco could carry gas from suppliers in the Caspian region, notably those in the Shah Deniz field in Azerbaijan, to southern Europe by 2017.
A smaller version of the planned 2,400-mile pipeline, dubbed Nabucco West, would move gas from the Turkish border to Austria, about half of what's expected for the entire project.
Nabucco is one of the projects outlined in the so-called Southern Corridor of gas transit networks for Europe. Its intent is to break the Russian grip on the regional markets by adding diversity to the natural gas sector.
"Nabucco is the flagship project in the Southern Corridor because it is the best commercial and strategic option to diversify gas supply of Bulgaria, and Europe," said Mitschek.
Sofia this week also threw its support beyond Nabucco counterpart South Stream, a project planned by Russia.