In the public pools of the French alpine town of Grenoble, women are not allowed to swim in burkinis.
The supreme administrative court, the Council of State (Conseil d'État), on Tuesday rejected a complaint by the green city administration.
Green mayor Éric Piolle appealed against an injunction by the administrative court in Grenoble that revoked the burkini permit he had granted.
The State Council now agreed with the administrative court.
The new bathing regulations were decided "to satisfy religious demands" and exempt a certain category of swimming pool users from the general hygiene rules.
This cannot be justified in the name of treating all users equally.
Grenoble was the first city to experiment with the burkini permit.
At the hearing before the Conseil d'État, the mayor showed different burkini models.
He advocates complete freedom in the swimming pools and wants to allow both topless bathing and full-body swimsuits.