The United Nations human rights office has called on French beach resorts to lift their bans on the burkini, calling them a "stupid reaction" that did not improve security, but fuelled religious intolerance.
France's highest administrative court last Friday suspended one seaside town's ban on the full-body swimsuit sometimes worn by Muslim women, with the reason that it violated fundamental freedoms.
UN High Commissioner for Human Rights Zeid Ra'ad Al Hussein welcomed the decision by the Conseil d'Etat against the Mediterranean resort of Villeneuve-Loubet, his spokesman Rupert Colville said.
A dozen other towns also have such bans.
"We call on the authorities in all the other French seaside towns and resorts that have adopted similar bans to take note of the Conseil d'Etat's ruling that the ban constitutes a grave and illegal breach of fundamental freedoms," he told a briefing.
"We urge all remaining local authorities which have adopted similar bans to repeal them immediately."
The "highly discriminatory" bans should be lifted before the summer holiday season ends, Colville said.
Bans have been defended on the grounds that burkinis violate French principles of secularism.
They come after mass killings by DAESH terrorists in France over the past 20 months.
Colville said the UN rights office understood the grief and anger generated by the attacks.
But he said of the burkini ban: "It's frankly a stupid reaction to what we are ... facing, in terms of terrorist attacks. It does nothing to increase security, it does nothing to improve public order."
Such decrees "fuel religious intolerance and the stigmatisation of Muslims in France, especially women", he said.
They "may actually undermine the effort to fight and prevent violent extremism, which depends on cooperation and mutual respect between communities".
The bans were "nothing to do with health or hygiene", as argued by some French officials, Colville said.
"And it's a complete contradiction to think we liberate people from clothing impositions by making other clothing impositions. So the idea that by banning this form of clothing you are somehow advancing women's freedom is complete nonsense."
This comes after former French president Nicholas Sarkozy said on Monday he would change the country's constitution to ban full-body burkini swimsuits if he is re-elected to his former role in a vote next April.