French police on Thursday said they were questioning three persons caught with two drones outside a nuclear power plant in the central Cher region.

However, the police added that the trios were not believed to be behind other drones spotted over several other nuclear facilities recently.

The two men and a woman, in their 20s or 30s, were arrested around 100 metres from the Belleville-sur-Loire plant on Wednesday.

A local investigating magistrate said they were suspected of having flown two drones close to the plant, violating a ban on the airspace above nuclear facilities.

However, the three were not suspected of being the perpetrators of the overflights of other nuclear plants, the magistrate told AFP news agency.

No fewer than 15 of France’s 19 nuclear plants have been targeted by mystery drone overflights in October.

The government has attempted to downplay the enigmatic “game of drones’’ as Liberation newspaper called it – a play on the title of the TV series Game of Thrones.

“These overflights of plants present no risk for the plants, which are built to withstand earthquakes and even falling planes,’’ Environment and Energy Minister, Segolene Royal said.

Environmental groups accused the state of being cavalier about the plants’ safety.

Greenpeace, which has staged several invasions of nuclear plants in the past two years to highlight what it sees as their vulnerability to attack, has called the drone overflights “very worrisome.’’

However, the group has denied being behind the phenomenon.

France is the most nuclear-dependent country in the world, while three-quarters of the country’s electricity is produced by 58 reactors.