The increasing number of violent attacks on teachers is prompting some schools to spend thousands of pounds on self-defence classes for their staff.

At a London hotel last week, more than 60 headteachers gathered to see a demonstration of techniques designed to fend off attackers.

They watched as health service staff showed them how to deal with attempts to strangle them, catch them from behind in a bear hug or grab their wrists.

“I’m not surprised schools are facing these problems. Children are more aware of their rights and they don’t have the same inhibitions and respect for authority they used to have,” said Jo Spencer, demonstrating self-defence techniques on the hotel lawn. She runs an acute psychiatric hospital and is used to getting out of dangerous situations.

She is also a member of the NHS-funded Self Security Services, which teaches hospital staff how to defend themselves against a massive increase in the number of attacks by members of the public.

The one-day conference, organised by the National Association of Head Teachers and titled “Managing Very Challenging Pupil Behaviour”, heard a stream of horror stories of staff facing violence in the classroom.

They were told of a teacher who was pushed against a wall by a 16-year-old boy with one hand over her mouth and nose and the other strangling her. She escaped only when a colleague arrived.

In another recent incident, a teacher was forcibly carried to her car, while another had her head repeatedly struck against the floor.

They also heard of cases where tens of thousands of pounds have been paid in compensation to teachers injured by pupils.

George Matthews, until last year a senior teacher in a special school for pupils with behavioural problems in south London, now runs his own consultancy teaching methods of self-defence and restraint learnt on a study tour of schools in the United States.

Since Christmas he has been busy visiting special schools, primary schools and comprehensives, giving tuition that ranged from one-day introductions to four-day courses. Schools are paying up to pound;2,000 to put five teachers through the longer course.

His “team teach” method aims to show how dangerous situations can be defused through “aggression management”.

“It’s all about how to break away from a potentially difficult situation in a way that doesn’t inflame the aggression,” he says. “Schools are waking up to the fact that they have a responsibility to protect the health and safety of their employees. It’s either that or having to pay thousands of pounds in compensation.”

Unruly pupils are not alone in posing a threat. Nigel Ashton, head of a primary school in Tameside, Greater Manchester, told of parents, sometimes drunk or on drugs, confronting teachers.

“I’ve been threatened many times by irate parents,” he said. “They think if they’ve got a problem they can go and thump the teacher. I’m getting sick and tired of parents threatening us and making verbal attacks.”

Another more insidious problem highlighted by the conference is of the increasing number of pupils accusing teachers of using violence against them.

The NAHT deals with around 25 such cases a year, several times as many as in 1989 when the Children Act made such complaints easier, and classroom teachers’ unions report even higher figures. Only a handful of these cases go to court; even fewer end in guilty verdicts.

The potential threat to careers and personal integrity, however, has forced the unions to consider how it can protect their members against wrongful accusations.

Last year’s Education Act spelled out the kind of restraint teachers can use to control violent and aggressive pupils - it all boils down to using “reasonable” force - and the teachers’ unions have joined forces to produce a code of conduct giving guidance on what is allowed, which is due out later this year.