A petition of more than 30,000 signatures in support of the NASUWT union's campaign will be presented in the House of Commons on Wednesday.

The signatures were gathered by the union over the past six months.

MP Claire Curtis-Thomas will hand in the petition after a private members' debate on witnesses in sex abuse cases.

The union wants teachers who have been accused of abusing or assaulting pupils to be given anonymity until they have been convicted.

They argue that most teachers who are accused are subsequently cleared - but the damage to their careers and personal lives can be irreparable.

The NASUWT said police had investigated an average of 12 members accused of physical or sexual abuse of pupils every month in recent years.

Anonymity will strengthen the crucial principle of innocent until proven guilty Chris Keates, NASUWT

Of the 2,000 investigations against members, less than one in 25 resulted in convictions, the union claims.

Chris Keates, acting general secretary of the union, said: "NASUWT's campaign aims to secure amendments to legislation to give anonymity to teachers facing the trauma and stress of false accusations of child abuse.

"The Private Members' Debate will highlight the vulnerability of teachers facing malicious allegations and I welcome the support of Claire Curtis-Thomas MP who has been a vigorous campaigner on these issues.

"The Secretary of State, Charles Clarke, also expressed his wish to give consideration to how anonymity may be secured when he spoke at NASUWT's Annual Conference in April this year."

The union was not trying to protect abusers, she stressed.

But false claims caused so much stress that three NASUWT members had committed suicide, said Ms Keates.

"Anonymity will strengthen the crucial principle of innocent until proven guilty."