Bulgaria wants the European Commission to revive plans for the Nabucco pipeline that would pump gas from the Caspian Sea, after a Russian project seen as a rival was scrapped, Prime Minister Boiko Borisov said.
Keen to diversify its energy supplies due to the Ukraine crisis, Bulgaria meets more than 80 percent of its gas needs with imports from Russia.
Sofia was caught off guard by President Vladimir Putin's surprise announcement in December to abandon plans for the South Stream pipeline that would have supplied gas to Europe via Bulgaria, while bypassing Ukraine.
Nabucco was backed by Western powers, but was shelved in part because there was not enough demand to sustain both it and South Stream. Bulgaria, which would have benefited from charging transit fees for South Stream, sees reviving Nabucco as a way to compensate for its loss.
Moscow is now working on an alternative that would pass through Turkey but avoid Bulgaria, prompting accusations from Brussels that Russia was holding European Union member Bulgaria to ransom.
"We want to unfreeze the Nabucco project through Bulgaria," Borisov told reporters after meeting Azeri President Ilham Aliyev in Sofia.
"It is not aimed against anyone, this is about preserving Bulgaria's national interest, so that our gas network be full with gas, so that we take transit fees and not be bypassed," Borisov said.
European leaders had pushed Nabucco in order to weaken Russia's grip on the Central and Eastern European energy market, but the project was derailed by cost overruns, a lack of available gas and Russian lobbying.
The Trans-Adriatic Pipeline (TAP), a rival project to Nabucco that will bring Azeri gas to Italy via Greece, is still under consideration.
Speaking alongside Borisov, President Aliyev said Bulgaria could build an interconnector with Greece to draw gas from the TAP route, which could then be sent on to Romania and Hungary.
Azerbaijan, whose total gas reserves stood at 2.5 trillion cubic metres, is expected to start shipping Caspian gas to Europe from its biggest gas field, Shah Deniz II, in 2020.
"We think that we can unite TAP and Nabucco. It is not important what you call this route. Our main goal is that the volumes of Azeri gas enter Europe," Aliyev said. "The more EU countries receive our gas, the better for all."