France's highest administrative court has suspended a Mediterranean town's ban on full-body burkini swimsuits.
Muslims have been outraged by the ban, which was imposed by the mayor of Villeneuve-Loubet on the grounds that the women's swimwear posed a threat to public order and contravened French laws on secularism.
The court has found there is no evidence of a threat, and has ruled in favour of the League of Human Rights, which argued the ban contravened civil liberties.
It said Villeneuve-Loubet's ban had "seriously infringed, in a manner that was clearly illegal, fundamental liberties such as the freedom to come and go, religious freedom and individual freedom".
However, Socialist French prime minister Manuel Valls said the debate was not over, calling the outfit a symbol of a "backwards, deadly Islamism".
He said that France needed a modern, secular Islam and wearing a burkini clashed with that idea.
"The Council of State ruling does not close the debate on the burkini," Valls said on Facebook.
"Denouncing the burkini is not calling into question individual freedom ... It is denouncing deadly, backwards Islamism."
The ruling from the Council, which both advises the executive branch and acts as supreme court for administrative justice, in effect overturns similar bans in about 30 other French towns.
It is an interim decision while the court takes more time to prepare a judgment on the underlying legality of the case.
Many conservatives and right-wing French supported the burkini ban, with some calling for it to be extended nationwide, while civil liberties campaigners, feminists and Muslims opposed it.
The debate was fuelled by footage of police trying to enforce the ban on a woman on a beach in Nice.
The issue has filtered into early campaigning for the presidential election in April 2017, making French cultural identity as well as security a hot issue in political debates.
Former President Nicolas Sarkozy on Thursday launched his comeback bid on a hardline law and order platform.
A spokesman for the ruling Socialist Party and the rector of the Great Mosque of Paris, Dalil Boubakeur welcomed the court ruling and said he hoped it would calm things down.
Villeneuve-Loubet mayor Lionnel Luca, of Sarkozy's Les Republicains party, said the ruling would heighten tensions.
"We need to decide if we want a smiley, friendly version of sharia on our beaches or if we want the rules of the (French) republic to be implemented," he said, referring to the Islamic legal and moral code of sharia.