Muslim parents will be forced to send their children into mixed swimming lessons after a European Court of Human Rights (ECHR) ruling on Tuesday.
Switzerland won its case after the Strasbourg-based court ruled authorities had not violated freedom of religion after it fined two Muslim parents for removing their daughters from mixed swimming lessons.
The seven ECHR judges unanimously ruled that integration into "local customs and mores" come above the parents' desire.
The two Swiss citizens, of Turkish origin, bought the case to the ECHR in 2012 after a long-running dispute with the local authorities. They argued their beliefs prevented them from allowing their children to participate in mixed sex swimming lessons.
Children going through puberty can be given an exemption from swimming classes under Swiss law but the parents were told their children were not eligible at the time.
After a long dispute the parents were fined 1,400 Swiss Francs ($1,380, £1,136) for "acting in breach of their parental duty".
In its ruling the European court admitted religion freedom was interfered with but said the right was not violated.
The court upheld the national decision and noted the school had tried to make the lessons more acceptable by allowing the girls to wear burkinis if they wished.
In a statement on the ruling, the ECHR, said the school gave "a special role in the process of social integration, particularly where children of foreign origin were concerned".
It added: "The children's interest in attending swimming lessons was not just to learn to swim, but above all to take part in that activity with all the other pupils, with no exception on account of the children's origin or their parents' religious or philosophical convictions."
