France's capital Paris is on alert for a new terror attack after "at least" five drones were spotted illegally flying in the country around city landmarks, which include the U.S. embassy building, the Eiffel Tower and Bastille Square.
The Eiffel Tower
The unmanned aircrafts were also spotted flying overnight near the capital's Place de la Concorde and the Ivalides military museum where Napoleon Bonoparte's buried.
Operators of the drones were not caught by French security sources, but it's thought that they're the usual type, typically fitted with video recording equipment.
A police source in the capital said: "They could be seen throughout the night, but nobody knows who were operating them."
The drones have the ability to be used for surveillance of a terror attack so that security levels can be assessed and any spikes in pedestrian traffic can be looked at ahead of any planned attacks.
At around midnight, the first drone was spotted near the US embassy in Paris. Between then and 6am, a security source says that other city landmarks "were also flown over".
Asking not to be identified, the source explained: "It could be a co-ordinated action but we don't know for now."
"We did everything to try and catch the operators but they were not found," said another close to the investigation.
The past few months have seen a series of mysterious drone appearances take place in France, with a pilotless aircraft going over the presidential palace in Paris on January 20.
However, "there have never been so many drones appearing in one night" the security source confirmed.
After warnings by terrorist groups that they'll attack the city, the emergence of drones has the country on high alert, following shootings that also took place there in January which left 20 dead, including three terrorists.
French law bans small civilian drones from areas including nuclear facilities which are protected by no-fly zones, spanning a 1.6-mile radius and a height of 1,000 metres.
Experts say that no threat would be posed if the small unmanned craft's crashed into a hardened nuclear facility.
Earlier this month, France unveiled their own drone with a net in a bid to combat the growing menace of rogue drones flying through the air.
Meanwhile, an Israeli tourist found out the rules the hard way earlier in the week was he was arrested in front of Notre Dame Cathedral, after flying a drone above some of the top attractions in Paris.