Critics of hydraulic fracturing, also known as fracking, claim chemicals used in the process could contaminate water supplies. Advocates note that potentially harmful chemicals in fracking fluid account for less than 1 percent of the mixture, however.
Ukraine and Poland, other countries rich in shale, have plans to go ahead with the process. France, however, has banned fracking, though French supermajor Total said last year it would challenge the decision.
French Economy Minister Eric Besson told delegates at an international oil summit in Paris that oil and natural gas explorers haven't been able to prove fracking is safe.
"That doesn't mean the subject is closed," he was quoted by the Platts news service as saying.
Total officials, at the same conference, said there was room for improvement in terms of the safety of natural gas production.
Total had permits to explore around 1,670 square miles of land in southern France for shale natural gas deposits but they were revoked in October.