False allegations against teachers are increasing with pupils using social networking sites to co-ordinate claims, MPs heard today.

Hundreds of careers are left in tatters every year as a result of the accusations but only 5 per cent of them are ever proven, according to figures from teaching unions.

The rise in number of complaints against teachers is a result of greater awareness of child protection among pupils, the Children, Schools and Families Select Committee heard.

Julian Stanley, chief executive of the Teacher Support Network, said: “It may be that within these schools the young people have cottoned on that by making complaints they can achieve desired outcomes for themselves.”

Once an allegation has been made a teacher faces immediate suspension pending investigation. The suspension is viewed by parents, other staff and pupils as an indication of guilt, teaching charities and unions said.

One suspended teacher was banned from all public services in his area during his suspension, MPs heard, another was told not to contact anybody at the school — even though his wife was also a teacher there.

The unions claim that the system of dealing with allegations means teachers are presumed guilty before any evidence against them is gathered.

The use of social networking sites by pupils who collude against a teacher, is also on the increase, unions said. Fiona Hammans, from the Association of School and College Leaders, said: “There can be campaigns from certain groups of pupils who have taken a dislike to their teacher . . . that can lead to full investigations into allegations they make on social networking sites.”

One teacher discovered a hate campaign against him when his daughter, also a pupil at the school, found it being discussed on Bebo, a social networking website, a cross-party committee of MPs heard.

The committee is conducting an inquiry into the scale and nature of false allegations against teachers.

The number of teachers affected by malicious complaints is unknown because many do not make it as far as an official investigation.

But among members of just one union, the NASUWT, there were 192 allegations in 2007. Only seven led to cautions or convictions. In 1997 there were 118 accusations against members which ended in seven cautions or convictions.

Amanda Brown, head of employment, conditions and rights, at the National Union of Teachers, said some 200 allegations were brought against members every year in the last 10 years.

“The number that are proven is very small,” Ms Brown said. “This has a chilling effect on teachers that they may well be the subject of an allegation. The impact is so great that the fear is there and we are worried for members who are accused by also for the profession.”

Even when an allegation is shown to be untrue it remains on the teacher’s record and can be seen by future employers, a measure brought in following the Soham murders. Allegations against Ian Huntley did not show up on his record and enabled him to go on to be a caretaker at the school of his victims Holly Wells and Jessica Chapman.

Mr Stanley told The Times: “Allegations against teachers seem to be on the increase. They are overwhelmingly found to be untrue and the often protracted period between accusation and resolution, combined with a frequent assumption of guilt, ensures that many teachers, despite doing nothing wrong, are being put under severe emotional strain, the confidence in their own abilities undermined.

“We have seen too many occasions when teachers have been unable to return to work despite being cleared of the allegations.”

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