PARIS: Skies over the Paris region will be closed for six hours as part of the massive security operation for the July 26 opening ceremony of the Olympic Games, the Paris airports operations said Wednesday.

Augustin de Romanet, chairman of Aeroports de Paris, said airlines are being warned in advance about the closure and told they will have to fly around the restricted airspace.

“For six hours, there won’t be any aircraft over the Paris region,” he said on France Info radio. The no-fly zone will extend for a radius of 150 kilometers (93 miles) around Paris, the civil aviation authority and Interior Minister Gerald Darmanin have said.

The unprecedented waterborne ceremony on the River Seine running through the French capital is the stiffest single security challenge for Paris Games organizers, with crowds of more than 320,000 people expected to line the waterway.

At least one French military AWACS surveillance aircraft will police the skies during the Olympics, using its powerful radar to watch for any potential airborne threats, the French AWACS squadron’s commander previously told media. Other military aircraft can be scrambled to intercept any non-authorized flights that enter restricted Olympic airspace.

Separately, de Romanet said there’s still a “very, very high” probability that small electric-powered airborne taxis will be trialled with passengers over Paris during the July 26-Aug. 11 Games, which he said would be a world first.