Nuns' habits are also banned from some French beaches, the deputy mayor of Nice has confirmed, as the furore over a ban on burkinis continues to rage.

Speaking on Radio 4 on Thursday, Rudy Salles defended the decision to ban burkinis, a form of swimsuit for Muslim women that leaves only the face, hands and feet exposed. He insisted the ban was a "necessity" after a series of terror attacks hit France in recent months.

"What is the burkini? There is bikini and there is burka and the burka is forbidden. When you go to the beach you wear a bathing suit. You don't go to the beach as you want. If I want to go on the beach naked it's forbidden – I cannot," Salles told the World at One's Edward Stourton.

"So if you want to go to the beach in a burkini it's forbidden because it is a provocation. Religion and the state are completely separated. Religion is the affair of each one but each one at home, each one at church, not each one in the street."

When asked whether a Catholic nun wearing a habit would be allowed on beaches in Nice, the deputy mayor replied: "No. The same [ban would apply]."

The comments came after the secretary general of the Italian bishops' conference criticised the ban.

Bishop Nunzio Galantino said in an interview with Corriere della Sera: "It's hard to imagine that a woman [in a burkini] who enters the water is there to carry out an attack."

He added: "I can only think of our nuns, and I think of our peasant grandmothers who still wear head coverings."

He continued: "The freedom to be granted to religious symbols should be considered on a par with the freedom to express one's beliefs and to follow them in public life. And, let me tell you: I find it ironic that we are alarmed that a woman is overdressed while swimming in the sea!"

The row over the ban imposed in at least 15 French towns has divided the French government with the Prime Minister Manuel Valls clashing with his education minister Najat Vallaud-Belkacem.

Valls said the swimsuits represented "the enslavement of women" but Vallaud-Belkacem said the ban had "let loose" verbal racism.

"I think it's a problem because it raises the question of our individual freedoms: how far will we go to check that an outfit is conforming to 'good manners'?" she said.

France's high court began hearing arguments against the burkini ban from an anti-Islamophobia group and the Human Rights League on Thursday and is expected to rule on its legality.