REPUBLIKA.CO.ID, PARIS - French security officials are investigating a spate of mysterious and illegal flights by drone aircraft over more than a dozen nuclear power stations in France, raising security concerns in a country that largely lives off atomic energy.

In what environmental activists call a worrisome development, authorities have tallied at least 15 overflights of nuclear sites since early October, culminating Friday with five at separate sites, government and utility officials said Monday.

Authorities would not speculate about who could be behind the overflights or what their motive might be. But prospects ranged from would-be terrorist scouts, economic spies, a political or environmental group, or even a hobbyist playing an illegal joke. Environment and Energy Minister Segolene Royal said there are no leads as to who was behind the flights.

"We don't underestimate these incidents, we don't overdramatize them either," Royal told i-Tele TV, saying France's nuclear sites have been prepared for possible earthquakes or plane crashes and suggesting drones were a lower risk.

Drones have vaulted into public awareness in recent years, ranging from ones as large as planes used by the CIA to bomb terrorist suspects, to small ones bought by hobbyists and media organizations for fun or news-gathering activities.

The drones used at the nuclear plants were small, with some about the size of a large pizza box that can fly only a few meters in the air, and another about 2-meters (6-feet) wide that can go higher, one official told The Associated Press. The official spoke on condition of anonymity because she was not authorized to discuss the matter publicly.

Experts said drones are primarily used for reconnaissance missions.

"Drones can be used for collecting data in various ways, whether it be images, videos, air samples, for example, and sound," said Jean-Luc Fornier, a professional drone operator.

"We have no clue regarding who could be behind these operations... (But) whoever is behind this they have not been very careful since they have been spotted," he added.

French law prohibits individuals from operating drones in crowded areas, near airports, and near sensitive sites like military bases or nuclear plants, said Eric Heraud, spokesman for France's civil aviation authority.

Ikuti Whatsapp Channel Republika