Paris police on Wednesday said the public had reported around a dozen drone sightings over sensitive areas of the French capital -- the latest in a baffling series of overflights.
Authorities are now scrambling to work out "if all the reports were really drone flights," said a police source who declined to be named.
No arrests were made over the flights, which reportedly took place overnight Tuesday near the River Seine, the Place de la Concorde, the Invalides military museum and around the Paris ring road.
French authorities are still scratching their heads to find a motive for the drone flights, as Interior Minister Bernard Cazeneuve announced late Tuesday there had been around 60 incidents over nuclear plants or over Paris since October.
On Tuesday, a court fined a British journalist 1,000 euros ($1,100) for flying a drone over central Paris and confiscated his machine.
Tristan Redman, 34, from the Qatar-based network Al-Jazeera, was arrested last month in the Bois de Boulogne park on the western edge of the French capital along with two other journalists.
The two others were released and Redman pleaded guilty to flying a drone over the capital, which is illegal under French law.
Their arrest followed two nights of unexplained drone sightings over the French capital, although a source with knowledge of the case said the journalists were not involved in the earlier incidents.
Those mysterious sightings were made near the US embassy, the Eiffel Tower and several major thoroughfares leading in and out of the French capital, police said.
Police have been unable to catch any of the operators of the night-time flights and it is unclear whether they were the work of pranksters, tourists or something more malicious.
France remains on high alert after jihadist attacks in and around the French capital in January left 17 people dead.