French Energy Minister Segolene Royal said on May 10 she is investigating legal means to ban the import of shale gas from the U.S. because France has banned shale gas exploration using hydraulic fracking for environmental reasons.

Royal, answering a question in parliament, said contracts signed by French gas utility Engie SA and power utility EDF with a U.S. producer have led to the import of LNG which contained about 40% shale gas.

"I have asked the two companies why they weren't vigilant and I have also asked for an examination of a legal means for us to ban the import of shale gas," Royal said in parliament.