At least five unidentified drones were spotted flying over the Eiffel Tower and other central Paris landmarks overnight, raising security concerns.
The new drone sightings come amid a series of mysterious drone overflights at nuclear plants and more recently over the presidential palace, as well as at a time of heightened security following last month's jihadist attacks that left 17 people dead, the Associated Press reported.
However until now, authorities have been unable to catch the operators, sources close to the probe said on Tuesday.
"It could be a co-ordinated action but we don't know for now," a police source, who asked not to be identified, told the Agence France-Presse. "We did everything to try and catch the operators but they were not found."
On Tuesday morning, the first drone was spotted hovering near the U.S. embassy in the French capital just after midnight, prompting police to follow the unmanned aircraft which continued on towards the Invalides military museum.
But shortly after losing sight of the drone, they discovered four other pilotless aircraft hovering near several landmarks including the Eiffel Tower, the Place de la Concorde and the Montparnasse tower, the tallest skyscraper in the city.
According to another police source, so many drones had never been spotted over Paris in one single night.
"In October and November, around 20 of the unidentified aircraft flew over French nuclear plants and their operators were never found," according to AFP. "Then on January 20, a pilotless aircraft briefly went over the presidential palace in Paris, just a week after three days of jihadist attacks in Paris put the country on heightened alert."
"And at the end of January, small drones were spotted near a bay in Brittany that houses four nuclear submarines -- one of the most protected sites in the country."
Although the drones are not believed to present any current threat, the French government is attempting to find ways to counteract the devices.
Meanwhile, drones are known to come in all shapes and sizes, and have a variety of uses, from widely reported military applications to surveillance, filmmaking, sports, disaster relief and scientific research, according to Al-Jazeera.
