The 14-year-olds were sent home by Mount Carmel Roman Catholic High School at Accrington after talks to resolve the dispute failed.
Head teacher Xavier Bowers has stressed that the matter is not one of religion but about dress code.
In a statement issued today, he said: "At Mount Carmel RC High School, we believe that it's important to be clear about what we expect from students in all aspects of school life, including appearance and uniform.
"Pupils and parents are made aware of the rules on appearance and uniform before they start attending the school, know that they apply to everyone and are regularly reminded of this."
The matter was further complicated by the fact that two other boys were allowed to keep their beards towards the end of last year as their annual exams approached - but that was as an "exception" because the school did not want to place them under "unfair pressure".
