19 January 2012
Bulgaria has become the second European country after France to ban exploratory drilling for shale gas using the extraction method called "fracking".
Bread loaves symbolised nature at an anti-fracking
rally in the Bulgarian capital Sofia
Bulgaria has revoked a shale gas permit granted to US energy giant Chevron.
Critics say shale gas drilling can poison underground water and even cause earth tremors. Industry experts say correct drilling is safe.
Hydraulic fracking involves releasing gas trapped in rocks by pumping in water mixed with sand and chemicals at high pressure. The technique is used widely in Canada and the US.
The Bulgarian drilling ban stipulates a fine of 100m levs (£43m; $66m) for any infringements.
Last Saturday protesters rallied in several Bulgarian cities urging the government to halt drilling for shale gas.
Currently Bulgaria and many of its former communist neighbours rely heavily on imported Russian gas.
Chevron had been given a permit to prospect for shale gas in northeastern Bulgaria.