A survey of teachers in schools in the east of England uncovered 287 incidents over just 30 days last year.

Of those, one in four was said to involve a physical assault.

The study was carried out by the teachers' union the National Association of Schoolmasters Union of Women Teachers (NASUWT).

The union says that if the figures for Cambridge alone were extrapolated across England it means that every seven minutes, a teacher somewhere is facing abuse.

I have been physically threatened by a parent and verbally abused by pupils Teacher, Suffolk

Teachers reported being sworn at by children as young as seven and being verbally abused even by children in reception classes.

They told researches they had been bitten, scratched, kicked, punched and spat at.

In one case, a girl pushed a teacher over a desk while being "egged on by her classmates".

One teacher from Bury St. Edmunds, Suffolk, who asked not to be named, told BBC News Online the problem was widespread and increasing

"I have been physically threatened by a parent and verbally abused by pupils, but some of my colleagues in other areas have had a lot worse.

"One was sworn at for telling a boy not to throw a rugby ball around in the library. Another was shouted at in the street and called a paedophile, another was sent sexually abusive e-mails.

"It is very distressing, even for very experienced teachers, and it is demoralising."

National picture

General Secretary of the NASUWT, Eamonn O'Kane, said: "This survey demonstrates a very worrying picture and highlights the necessity for teachers and schools to record incidents of abuse.

"The survey unfortunately confirms the findings of a similar exercise in the North West region that these incidents of verbal and physical abuse reflect the national picture rather than localised problems."

The union says the system for reporting abuse should be simple and the penalties tough, including the use of temporary and permanent exclusions.

The union surveyed its members in 2,500 schools but says not all responded.

Defiance

Drama teacher Peter Smith, of Hewett School in Norfolk, says the problem of abuse has increased dramatically in the past two years.

He blames the government's policy of inclusion, which he says means that children with severe learning difficulties or behavioural problems are kept in an environment which is not suitable for them.

"It's not fair on them or on anybody else. They will not succeed there and will become disillusioned and disrupt the other pupils," he said.

"There is a lot of defiance and rudeness. It's as if some children live in a parallel universe, they don't recognise what they are doing wrong."