Paris: Three people were detained on Wednesday after authorities found them with at least one drone near a French nuclear plant, officials said, with unauthorised overflights of such sites having raised concerns in recent weeks.
The three people believed to be in their 20s were detained near a nuclear plant in Belleville-sur-Loire, some 150 kilometres south of Paris.
They were said to be in possession of at least one drone, but it had not flown over the plant.
Prosecutor Marie-Pierre Viret told AFP the three were held for questioning over "voluntary overflight ... of an aircraft in a prohibited area."
French law bans small, civilian drones from areas such as nuclear facilities, which are protected by a no-fly zone that spans a 2.5-kilometre (1.6-mile) radius and a height of 1,000 metres.
French authorities have been left scratching their heads as unidentified drones zoom over nuclear plants across the country.
A drone had previously been detected around the plant at Belleville-sur-Loire, though it had not crossed the security perimeter.
While they pose no danger to the rock-solid structures, the mysterious phenomenon raises several concerns, experts say.
State-run power company EDF rang alarm bells last week when it announced it had filed a complaint with police after detecting the small unmanned aerial vehicles zipping over seven atomic plants in October.
Since then, more have been spotted and there have been at least 16 fly-overs throughout France, usually at night, leaving jittery authorities clueless as to who is piloting these helicopter-type machines at a time of heightened vigilance in the face of Islamic extremism.
Some experts say they believe the recent spate of mystery fly-overs is probably being carried out to prove a point about nuclear security.