The city of Nice, still shaken by last month's deadly extremist attack, has joined a growing list of French sites to ban the body-covering burkini swimsuit.
Leading officials argue that the swimwear, resembling a full-body wetsuit with a hood, oppresses women and violates France's secular principles.
But many see the bans as discriminatory.
Nice was devastated when a truck driver attacked crowds watching fireworks on July 14, killing 85 people in violence claimed by the Islamic State group.
About a third of the victims were from Nice's large Muslim community, which is both in mourning and fearing a backlash.
The Nice administration issued an order on Thursday banning swimwear with religious connotations, citing security concerns.
Several other cities on France's Mediterranean and Atlantic coasts have banned burkinis this summer.