French officials have banned a Muslim woman from swimming in a public pool while wearing a swimsuit that covers her entire body.
The woman had swum in July in the pool in Emerainville, east of Paris, in the "burkini" - a loose-fitting garment resembling a wetsuit with a hood.
But staff stopped her from swimming in August, citing hygiene concerns.
It comes as the government examines ways to limit burka use after the president said they reduced dignity.
France is home to Western Europe's largest population of Muslims, with about 5 million living there.
At the pool, staff "reminded [the woman] of the rules that apply in all (public) swimming pools which forbid swimming while clothed," pool management official Daniel Guillaume was quoted by AFP as saying.
The woman was a French convert to Islam, and had bought the swimsuit in Dubai so that she would not have to uncover herself to go swimming.
"Quite simply, this is segregation," she said, according to Le Parisien newspaper, which identified her only as Carole.
"I will fight to try to change things. And if I see that the battle is lost, I cannot rule out leaving France."
Emerainville Mayor Alain Kelyor said "all this has nothing to do with Islam", adding that the swimsuit was "not an Islamic swimsuit" and that "that type of suit does not exist in the Koran".
'Prisoners behind netting'
In June the French National Assembly appointed 32 MPs to a six-month fact-finding mission to look at ways of restricting burka use.
In a major policy speech that month, President Nicolas Sarkozy said the burka - a garment covering women from head to toe - reduced them to servitude and undermined their dignity.
"We cannot accept to have in our country women who are prisoners behind netting, cut off from all social life, deprived of identity," Mr Sarkozy told a special session of parliament in Versailles.
In 2004, France banned the Islamic headscarves in its state schools.