A teacher in a Catholic school forced two Sikh children to remove their turbans breaking the law, according to Schools Week.
Prasimran Kaur, 11, and Simranjot Kaur, 13, who are not related, were both told to remove their religious headwear by a teacher at St Ann's Catholic School in Southampton, who then tried to forcibly remove the turban from the older girl.
Schools are prohibited from discriminating on grounds of race, sex or other "protected characteristics" under the 2010 equalities acts. This applies to turbans.
The Sikh Federation wrote a letter to education secretary Nicky Morgan, in which chair Bhai Amrik Singh said the organisation was considering legal action, and demanded the teacher concerned to be suspended pending investigation.
"This was an appalling incident given Sikhs successfully fought for the right for Sikh children to wear the turban over 30 years ago in the landmark Mandla v Lee case in the House of Lords in 1983."
He added that it was "totally unacceptable and highly offensive that a teacher not only physically touched the turban, but also started unravelling it, leaving the girl distressed and in tears."
Morgan said the teacher concerned had made a "serious error," and insisted that her department expected schools to "take responsibility for putting in place processes to handle complaints from parents."
The event, which led to the parents of the two girls temporarily removing their daughters from school, was described as a "misunderstanding" by the head teacher Lyn Bourne. She apologised for "any offence caused."
She said "The situation that occurred was a misunderstanding and I can confirm that both girls involved now have permission to wear a turban to school. These should be plain navy blue or black until we are able to identify an appropriate supplier. St Anne's is an inclusive school community that respects all faiths. We are united by our shared values and do not allow ourselves to be divided by our differences."
The Catholic Education Service wrote in its guidelines that "respect for other faiths should be a mutual obligation."
A spokesperson said all Catholic schools should follow government guidance as well as their own.
