Parents and former pupils at North London Collegiate School have expressed their shock over an incident in which a teacher told a Jewish pupil she would be “sent to a gas chamber”.

The outburst happened at the £6,000-per-term girls’ school in Edgware when the 17-year-old, who has not been named, jumped the lunch queue.

The teacher reportedly told her: “Don’t do that or I’ll have to send you to the back of the queue or to one of your gas chambers.”

Parent Rabbi Jonathan Wittenberg, whose daughter is in her final year at the school, said it was “completely out of character and surprising for a school that has a lot of Jewish pupils and has always been friendly and supportive of them”.

Claire Pozner, a retired teacher and former pupil at the school, said she was “gobsmacked.

“This is the last place anybody would expect to hear about something like that,” she said. “I think the situation sounds like a complete one-off, but it is still very shocking.”

The pupil’s father has complained that the school has not done enough to highlight the severity of the incident.

Though the teacher made a private apology to the family, the school has refused to name her or state whether any disciplinary measures were taken.

A spokesperson for the school, which caters for more than 1,000 pupils aged 4-18, said: “The school was recently made aware of an allegation of an offensive statement made by a member of staff. The school promptly commenced an investigation. Having reached a determination and sought specialist legal advice, appropriate action was taken.”

The incident was reported to the Community Security Trust. Communications director Mark Gardner said: “CST was deeply shocked that such a thing would be said by a teacher to a pupil. We have been working closely with the family and the school to try to resolve matters.”