After a series of changes in the law and recommendations from a Government working party on school security following the death of London headmaster, Philip Lawrence, the Government is issuing guidelines to help schools deal with troublemakers.
A Government-commissioned survey earlier this year found that pupils had brought in weapons at one in ten schools but heads were afraid to report incidents for fear of bad publicity.
Teachers have repeatedly complained about the difficulty of dealing with violent incidents in school when they are in danger of being accused of assault or abuse by parents.
From April 1998, they will have protection under the Education Act 1996 if they use reasonable force to restrain pupils to stop them causing injury, committing a crime, damaging property or causing disruption.
The guidance also reminds teachers that it is an offence to carry offensive weapons in school under the Offensive Weapons Act 1996.
Only a folding pocket knive with a blade of less than three inches is allowed. Schools, however, may wish to ban these, the guidance from the Department for Education suggests.
Police should always be called if a knife or weapon is found. If teachers feel they must take action to remove the weapon before police arrive, they should not confront pupils with weapons until they have been diverted to part of the school where there are no other pupils. They should only search a pupil who agrees to co-operate.
Knives in school are permitted only for use in lessons such as cookery, for religious reasons (for example, a Sikh's kirpan) and as part of national costume.
Teachers are advised how to deal with the growing problem of trespass by parents or strangers. The Government survey found that parents had caused serious disturbances at a quarter of schools. Schools should make clear that parents may be trespassing if they come into school uninvited, says the guidance. If trespassers persist in entering a school, the school or local authority can seek an injunction against them.
Ministers yesterday promised an extra pounds 2m for equipment such as closed- circuit television and training for staff.
Estelle Morris, the schools minister, said: ``Nuisance, disturbance, vandalism and other problems are all too common in our schools and this guidance will be an invaluable source of information which helps to ensure that the laws available to deal with these problems are better understood and more consistently applied.
``I am confident that the guidance will encourage schools, local authorities and the police to adopt and share sensible partnership approaches to dealing with problems."