The French city of Grenoble on Monday allowed Muslim full-body swimsuits, so-called burkinis, in public swimming pools.
After three and a half hours of controversial debate, a slim majority of the city councilors voted for a corresponding change in the swimming pool regulations.
The green mayor of the city, Éric Piolle, started a nationwide burkini debate with the plans.
Critics spoke of a creeping Islamization, while Piolle wants to give women the choice to wear as much or as little as they like in the water.
Going topless is also allowed in the future.
Prefect Laurent Prévost had already announced legal action on Sunday evening if burkinis were to be given the go-ahead in public baths in Grenoble.
According to the instructions he received from Interior Minister Gérald Darmanin, he will go to the administrative court to have the regulation suspended.
2016 burkini ban ruled illegal
There was already a heated argument about burkinis in France in the summer of 2016, and there were also local bans.
Finally, the Council of State declared a municipal burkini ban, as enacted on the Côte d'Azur, to be illegal.
Municipalities then used hygiene and safety justifications to continue banning burkinis from beaches and baths.
France sees itself as a secular country in which there is a strict separation of state and religion.
The handling of religious symbols in public has repeatedly caused controversy, especially in connection with Islam.