A scientific study in Poland has found that shale gas extraction at one site produced some toxic refuse but that the waste was reused and didn't harm the environment.

The report was presented today by the Polish Geological Institute, which carried out its study last year when a company, Canadian Lane Energy, began test drilling near Lebien, in northern Poland.

Poland has some deposits of shale gas and is hoping to exploit them to cut its dependence on Russian natural gas. It hopes to repeat what has happened in the United States, where large shale gas discoveries in the past 10 years have given the country independence in the gas sector.