In the wake of an Orthodox Jewish day school in Stamford Hill redacting questions about evolution from a national science exam, England’s exams office said the practice is not permissible.

The UK Office of Qualifications and Examinations Regulation, or Ofqual, sent a message to all public exam boards saying that blocking out questions on national exams is “malpractice” and “should not be allowed,” a spokesman for the office told the BBC.

The spokesman acknowledged that the practice was “very rare,” the BBC reported on Monday.

“Denying learners access to all the questions on a paper prevents the candidate achieving their full potential and therefore disadvantages them. It also threatens the validity of the qualification,” the spokesman said.

The message was in reaction to the reports that earlier this month that the Yesodey Hatorah Senior Girls’ School in Stamford Hill blacked out questions about evolution in a General Certificate of Secondary Education science exam.

A representative of the National Association of Orthodox Jewish Schools told the BBC that the association was seeking advice on this “very concerning matter.”