Pictures have emerged of French police appearing to enforce the controversial "burkini ban" on a woman on a beach in the southern city of Nice.
Police appear to issue a fine to the woman, who is then seen removing a veil and baring her arms.
Nice's deputy mayor said the removal of burkinis was a "necessity" after the deadly jihadist attack last month.
The French Council of the Muslim Faith (CFCM) expressed concern at the direction the public debate was taking.
A bid to overturn the ban is due to come before France's highest administrative court on Thursday.
The incident, which took place on Tuesday, happened close to the site of the jihadist attack on Bastille Day in July.
Rudy Salles, the deputy mayor of Nice, said: "It's a necessity after... the 14th of July on the Promenade des Anglais.
"It is not the habit and the custom of the Muslims in Nice to wear [clothes] like this on the beach."
Since the photographs went viral, Anouar Kbibech, the president of the CFCM, said he was "concerned over the direction the public debate is taking", citing the "growing fear of stigmatisation of Muslims in France".
Interior Minister Bernard Cazeneuve has agreed to a meeting with the CFCM.
Among many remarks about the incident on Twitter, the European Media Director of Human Rights Watch, Andrew Stroehlein, wrote: "Question of the day: How many armed policemen does it take to force a woman to strip in public?"
It is not clear from the photographs if the woman was ordered to remove items of clothing by the police, or if she did so of her own accord.
The 34-year-old mother, who gave her name only as Siam, told the AFP agency that she had been sitting on the beach in leggings, a tunic and a headscarf, when she was fined.
She said: "I had no intention of swimming."
The mayor of Cannes' ruling
- "Access to beaches and for swimming is banned to any person wearing improper clothes that are not respectful of good morals and secularism"
- "Beachwear which ostentatiously displays religious affiliation, when France and places of worship are currently the target of terrorist attacks, is liable to create risks of disrupting public order"
- The infringement is punishable with a fine of €38 (£33)
- The ban remains in place until 31 August 2016
The Muslim rights group, Collective against Islamophobia, said that 16 women have been given fines in the past fortnight on the Riviera under the ban - but argues that none were wearing a burkini.
The group said they were all wearing headscarves, tops and leggings.
BBC Paris correspondent Hugh Schofield says the so-called burkini ban actually makes no mention of the burkini.
The rules simply say beachwear must be respectful of good public manners and the principle of secularism which, he says, leaves large room for interpretation and confusion.
The controversial rules surrounding swimwear have been imposed by more than 20 municipalities in France.