Hundreds of French nudists are planning to take on a group of Muslim women fighting for the right to swim in public wearing burkinis.
As France swelters in the biggest heatwave in years, Muslim women have broken public pool rules in Grenoble by turning up in swimwear that conforms to their conservative religious requirements, local media reported earlier this week.
Comparing themselves to US civil rights icon Rosa Parks, the women say they're defending "freedom of religion".
The rules at the Jean Bron pools currently forbid burkinis, the Telegraph reports.
The group, numbering about 15, have bathed twice so far - each was fined €35 the second time. But at a third planned protest bathe scheduled for Sunday, they'll face a rival protest from nudists.
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Hundreds have signalled on Facebook they'll be showing up nude to protest the "burkini brigade".
"These are not poor Muslim mums wilting in the heat but political militants at work," said Amine El-Khatmi, president of left-wing French pro-secular group Republican Spring.
On his Twitter account, El-Khatmi called the women "militant bigots", saying if men had to wear speedos - as are the rules - women should have to stick to tight-fitting one-piece suits.
"In all the municipal swimming pools in the country, the wearing of shorts is forbidden for men in the name of hygiene. In the name of what should we tolerate women come swim covered from head to toe? Political Islam is a plague... You can cover me with insults and accusations of Islamophobia, I do not care."
The local Mayor put the debate in the too-hard basket, calling on the state government to "remove all ambiguity on the status of body-covering swimming costumes".
The burkini-wearers and nudists might have to find somewhere else to face-off, however - French media reports the lifeguards at the Jean Bron pools have downed tools, unable to concentrate on their lifesaving work.
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Despite the country's large Muslim population, French officials have taken a stronger stance against the religion than most liberal democracies, including a ban on face coverings such as the niqab.