More to this story

A team of Al Jazeera journalists has been questioned by the French police for flying a drone in the Bois de Boulogne park on the western edge of Paris.

Al Jazeera spokesperson said in a statement on Thursday that three of its journalists were "released after spending 19 hours in custody".

"Our staff in Paris were attempting to illustrate a piece to camera on domestic drones which are widely available, while also attempting to cover the recent drone mysteries in Paris and wider security concerns in France," the statement by the Doha-based Al Jazeera Media Network said.

"Al Jazeera prides itself in the integrity of our content and constantly strives to provide a full picture and context behind the story for our audience."

Their arrest followed two nights of mysterious drone sightings over the French capital, although a source with knowledge of the case said the journalists were not involved in the earlier incidents.

Unexplained sightings

Those unexplained sightings were made near the US embassy, not far from the Invalides military museum, the Eiffel Tower and several major thoroughfares leading in and out of the French capital, police said.

Flying drones over the capital is illegal under French law.

In October, a 24-year-old Israeli tourist spent a night in jail and was slapped with a $450 fine for flying one above the Notre Dame cathedral.

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.

"People should not be worried but vigilant, it's an issue which is taken very seriously," Stephane Le Foll, a government spokesperson, said earlier this week.

Surveillance denounced

Le Foll pointed out that drone flyovers had taken place in other countries such as Germany, where a small unmanned aircraft operated by activists denouncing police surveillance landed just metres away from Chancellor Angela Merkel during a 2013 campaign event.

And last month in Washington DC, a small drone crash-landed on the grounds of the White House, prompting a security lockdown.

French authorities were first alerted to mystery drone flyovers in October, when state-run power company EDF filed a complaint with police after detecting the small aerial vehicles zipping over seven atomic plants across the country.

The sightings continued into November, and altogether some 20 flyovers took place over nuclear plants.

Their operators were never found.

Then on January 20, a pilotless aircraft briefly flew over the presidential palace in Paris, not long after attacks in and around Paris left 17 people dead and put the country on high alert.

Source: Al Jazeera and agencies