"Chevron, which won the tender, offered the government a 30-million-euro (43-million-dollar) bonus for the licence to explore a shale gas field near Novi pazar. It won in competition with Canadian BNK," Traikov told a press conference.
Two more tenders for shale gas exploration in the same region in northeastern Bulgaria were still underway with offers to be submitted by end-June, Traikov added.
Inital estimates of the companies interested in shale gas exploration in Bulgaria put the country's deposits between 300 billion and 1.0 trillion cubic metres, he explained.
Bulgaria, which is almost totally dependent on Russian gas supplies via Ukraine, sees shale gas as a possibility of diversifying its energy sources.
Bulgaria also hopes to link its gas transportation network to neighbouring Greece in 2014 and receive gas from Azerbaijan via an interconnector system.