Bulgaria's parliament imposed on Wednesday an indefinite ban on shale gas exploration and extraction using hydraulic fracturing, or fracking.
A total of 166 MPs in the 240-seat legislature voted in favour, six were against and three abstained, the National Assembly said in a statement published on its website.
The ban applies to Bulgaria's whole territory and the country's Black Sea territorial waters.
Offenders will be fined 100 million levs.
Companies that hold permits to explore and extract gas using the controversial method have three months to submit for approval new working projects that exclude it. Those that fail to do so will lose their permits.
In July 2011 Bulgaria's government granted the local unit of on U.S oil company Chevron, Chevron Bulgaria Exploration and Production, a five-year oil and gas exploration licence.