Teachers who have faced repeated false accusations from pupils could be banned from schools by a new vetting organisation.

Unions say government officials are considering guidelines under which teachers with six or seven unproven accusations against them of physical or sexual harm could be deemed “unsuitable to remain in the profession”.

Jim Quigley, legal officer for the NASUWT teachers’ union, said he was alarmed to discover the proposal during discussions with officials over a new vetting watchdog.

The Independent Safeguarding Authority (ISA) will next year take over the vetting of 11.3 million people in the UK who work with children and vulnerable adults, including all teachers. It will be able to consider any police data on a Criminal Records Bureau enhanced disclosure, even if it contains unproven allegations.

A spokesman for ISA said the authority was entitled to take into account “all information regarding an individual” in reaching a decision on whether they present a risk of harm and whether they should be barred from teaching.

But Mr Quigley said malicious pupils could easily destroy teachers’ careers if extra weight was given to repeated, unproven allegations. Teachers and support staff in difficult environments, such as pupil referral units or special schools, could face that many accusations without doing anything wrong, he said.

David Bell, a Northern Ireland teacher, was falsely accused of indecently assaulting a 12-year-old girl. He pleaded guilty to a lesser charge of common assault and was given an absolute discharge.

But a school representative repeated some of the original allegations on radio. Mr Quigley said NASUWT lawyers threatened to sue for defamation. The South Eastern Education and Library Board agreed to pay Mr Bell damages.

Mr Bell said: “The stigma attached to an allegation is just too much for teachers to survive - it just destroys them.”

Two Court of Appeal judgments have supported decisions by police to disclose adverse information, even though it did not result in prosecutions or convictions.

In one, a children’s social work agency refused to employ a man after police revealed an allegation of rape and indecent exposure, although the case never went to trial.

The ISA was supposed to begin its vetting work this year, but had to postpone it until next year to ensure it can protect people’s private data.

It emerged last week that the agency had bungled the vetting of its own staff, inviting those who failed a psychometric test to interviews, and rejecting those who passed.

Mary Bousted, general secretary of the Association of Teachers and Lecturers, said it was hardly reassuring to find that the body charged with vetting the UK’s school staff could not vet its own job applicants.