An investigation is under way following reports that a vulnerable pupil was allowed to self-harm using a razor under the supervision of one of her teachers.
Teachers at Unsted Park School - which offers education to children aged between nine and 17 who have Asperger's syndrome and higher-functioning autism - allowed her to cut herself under controlled conditions, according to the Surrey Advertiser.
Staff were told they must escort the pupil to a bathroom where she would be allowed to self-harm in a "safe and controlled manner" before having her wounds properly cleaned and dressed.
The policy was dropped after a few days at the school in Godalming, Surrey, following protests from other members of staff. Some complained to Surrey County Council.
Principal Steve Dempsey and headteacher Laura Blair were under investigation by the Teaching Agency amid allegations of unacceptable professional conduct.
A spokesman for the Priory Group, responsible for running the school, said: "We are always willing to review cases with the Teaching Agency.
"This was a short-term, local procedure introduced by the headteacher and school principal who genuinely believed it was in the best interests of the pupil.
"However, they accept that the procedure should not have been implemented without further approvals having been obtained from key stakeholders and senior management prior to its introduction."
The policy was launched in January, but has only just been made public. It is believed the pupil's parents were aware of it.
The policy was criticised by charities and self-help groups.
Lucie Russell, from young person's mental health charity YoungMinds, said: "This policy is misguided and could be misinterpreted as encouraging young people to self-harm. It does not address the issues young people who self-harm are grappling with.
"What schools should be doing is providing supportive environments where young people are re-encouraged to talk about how they feel and helped to get the right support."
A spokeswoman from selfharm.co.uk, which supports young people affected by self-harm, added: "The best way to help is to listen without judging, accept that the recovery process may take a while and avoid 'taking away' the self-harm.
"Self-harm can be about control, so it's important that the young person in the centre feels in control of the steps taken to help them learn to manage without needing to hurt themselves."
The Department for Education said: "This is a deeply worrying allegation.
"The department commissioned an emergency inspection by Ofsted. It found some failings which we are working to rectify."