Two schoolboys have been barred from classes because they will not shave off their beards.
Both 14-year-olds, who are Muslims, were placed in "isolation" from the start of the new term at Mount Carmel Roman Catholic High School in Accrington.
The school's headteacher Xavier Bowers said the matter was not one of religion but about dress code.
Mr Bowers 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.
"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.
"When necessary, we place pupils in our learning support centre who do not comply with our school policy regarding uniform and appearance."
It is understood talks are ongoing between the families of the two boys and the school to resolve the issue.
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