PARIS, Feb 25 (Reuters) - French authorities have launched investigations into sightings of drones this week close to sensitive sites in Paris such as the presidential palace and the U.S. embassy, the government said on Wednesday.
Local media reported five sightings of drones overnight on Tuesday and Wednesday. There have been no claims of responsibility.
The Paris prosecutors' office said that, in an apparently unrelated affair, three Al-Jazeera journalists were arrested on Wednesday after being suspected of flying a drone in the western Paris park of Bois de Boulogne.
"There is no relationship for the moment between these arrests and the night-time fly-overs," said a spokesman for the prosecutors' office. No one was immediately available for comment at Al-Jazeera's Paris office.
The French capital remains on top security after last month's deadly attacks by Islamist gunmen at a satirical magazine and a Jewish food store.
However, government spokesman Stephane Le Foll ruled out a security risk and said drones were not solely a French phenomenon. "There is nothing to worry about," he told a regular news briefing.
"Drones have been spotted and investigations launched ... We are mobilized on a matter which is and should be taken seriously," he said.
Flying drones over Paris requires authorisation from the city, which was apparently not given for any of the recent flights. The five sightings follow a similar mystery last November involving overflights by drones of five nuclear power sites in the country. (Reporting by Elizabeth Pineau; Writing by Mark John and Alexandria Sage; Editing by Raissa Kasolowsky and Crispian Balmer)