Bulgaria is withdrawing US energy firm Chevron’s permit to drill for shale gas, according to reports. Last year Chevron initially won rights to explore shale gas reserves in the country with the hydraulic fracturing or ‘fracking’.

Shale gas is splitting opinion in Europe. While some countries like Poland are beginning projects to trial the unconventional fuel source, France – and now Bulgaria – are turning against ‘fracking’ for shale over environmental concerns it could contaminate local water supplies.

Currently the bulk of Bulgarian energy production is from nuclear and solid fuels such as coal, according to EU statistics.