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

(Reporting by Bate Felix, editing by Geert De Clercq)

Stocks treated in this article : Engie S.A., EDF