PARIS (Reuters) - France has launched an investigation into unidentified drones that have been spotted over nuclear plants operated by state-owned utility EDF , its interior minister said on Thursday.
Seven nuclear plants across the country were flown over by drones between Oct. 5 and Oct. 20, an EDF spokeswoman said, without any impact on the plants' safety or functioning.
"There's a judicial investigation under way, measures are being taken to know what these drones are and neutralize them," Interior Minister Bernard Cazeneuve told France Info radio on Thursday, without specifying the measures.
The drone sightings may renew concerns about the safety of nuclear plants in France, the world's most nuclear-reliant country with 58 reactors on 19 sites operated by EDF.
Activists from environmental campaigning group Greenpeace forced their way into the Fessenheim plant on the German border earlier this year and have a history of breaking into nuclear plants in France.
Greenpeace denied any involvement in the pilotless flight activity.
"For all its actions, Greenpeace always acts openly and claim responsibility," Yannick Rousselet, head of Greenpeace's anti-nuclear campaign, said in a statement. "What is happening is very worrying," he said, adding that France's nuclear research institute CEA near Paris had also been flown over, citing unspecified sources.
EDF named the plants over which drones had been spotted as Creys-Malville and Bugey in the southeast, Blayais in the soutwest, Cattenom and Chooz in the northeast, Gravelines in the north and Nogent-sur-Seine, the closest plant to Paris.
The unmanned aircraft were spotted late in the evening, at night or very early in the morning, EDF said. It is prohibited to fly less than 1,000 meters above nuclear plants and within a 5 kilometer radius.
Each plant has filed a formal complaint with the police against the anonymous people behind the drone flights.
(This story has been refiled to correct meters from kilometers in ninth paragraph)
(Reporting by Chine Labbe and Michel Rose; Editing by David Holmes)