A Muslim woman, wearing a full-body burkini swimsuit, walks on a beach in Cannes.
The French city of Grenoble has formally allowed Muslim women to wear burkinis, or swimming costumes covering the whole body, in public pools.
Members of the municipal council narrowly approved the new rules during a meeting on Monday despite political opposition.
After a tense debate, there were 29 votes in favour of the measure, with 27 councillors voting against and two abstentions.
France's interior ministry has stated that it will block the move, which contradicts French laws on secularism and the "neutrality of public service".
Gérald Darmanin described the decision as an "unacceptable community provocation, contrary to our values."
But the mayor of Grenoble, Eric Piolle, has repeatedly argued that debate over burkinis is a "non-issue".
Piolle has stated the change in swimming pool regulations – brought in before pools open in mid-June – aims to "remove aberrant clothing bans" and combat "injunctions on women's bodies".
From 1 June, Grenoble will relax its rules and allow both women and men to swim topless or wear full-body swimming costumes for sun protection or religious beliefs.
The move has been backed by women's rights activists in France, who have campaigned for people to "wear what they want" at swimming pools.
But MPs from the ruling En Marche party of President Emmanuel Macron have argued that Islamic veils go against France's strict secular values, which separate state and religion.
Opponents also argue that the burkini is a symbol of women's oppression, similar to the full veil that is worn in some Muslim-majority countries.
The right-wing president of the Auvergne-Rhône-Alpes has threatened on Twitter to pull all regional funding to the city over the new rules.
The regional prefect of Isère had announced on Sunday that he will refer the council's decision to the administrative court of Grenoble.
"I can't wait for the government to explain to us why we should hide all our religious signs in a swimming pool," Piollo told Franceinfo in response on Monday.
The Grenoble mayor has cited another French city Rennes, which passed a similar measure approving burkinis in 2018.
Two years earlier, an estimated 30 French coastal resorts banned women from wearing burkinis on beaches.
France's highest administrative court later ruled that the anti-burkini decrees were “a serious and manifestly illegal attack on fundamental freedoms”.
In Grenoble, the NGO Alliance Citoyenne has organised several recent stunts in the city's swimming pools to support the new rules.
The group has also campaigned against France's Football Federation, which bans the wearing of Islamic hijabs in competitions. — Agencies
FIFA World Cup Qatar 2022: Smoke-free stadiums and bans on tobacco marketing
Qatar Says it Will Adopt Climate Tech Application in FIFA World Cup 2022
World's deepest shipwreck discovered
Ministry urges public to participate in #WateringBirds initiative