Two Muslim schoolboys have been barred from classes because they will not shave off their beards.
Both 14-year-olds were placed in "isolation" from the start of the new term at Mount Carmel Roman Catholic High School in Accrington, Lancashire.
The school's headteacher said the matter was not one of religion but about dress code.
Xavier Bowers told the Lancashire Evening Telegraph: "We have not taken this decision lightly.
"I have spent quite a lot of time researching the issue and speaking to Muslim elders.
"There is nothing specifically written in the Koran about wearing a beard. It is a choice those boys are making.
"However inclusive we are, we have standards to maintain."
But a relative of one of the youngsters labelled the decision as "pure discrimination".
The family member, who did not wish to be named, told the newspaper: "Because these boys cannot shave their beards for religious reasons, they are being put in isolation for six-and-a-half hours every day.
"They are not being allowed to mix with anybody or speak to friends. It is pure discrimination.
"They chose that school because it is within their area and has good results. The school has to have an open policy and they have to take in people from all religions."
Mr Bowers added that the clean shaven rule had been in place for some time, although two boys were allowed to keep their beards on religious grounds as an "exception" last year as their GCSE exams approached and the school did not want to place them under "unfair pressure".
He said that a number of other Asian boys were then spoken to and it was made clear they must return from the summer clean shaven.
Following the newspaper interview, Mr Bowers today issued a statement via Lancashire County Council in which it appeared the school was not backing down from its stance.
He said: "I am fully aware of the sensitive nature of this issue and have done my very best to be as understanding and reasonable as possible when dealing with situations of this nature.
"When necessary, we place pupils in our learning support centre who do not comply with our school policy regarding uniform and appearance.
"Here at Mount Carmel RC High School, we believe that it's important to maintain high standards in every aspect of school life, including appearance and uniform. Pupils and parents are reminded frequently of the rules on appearance, know that they apply to everyone and are regularly reminded of this.
"In my experience, families choose to send their children to this school because of our high standards and expectations."
It is understood talks are ongoing between the families of the two boys and the school to resolve the issue.