Schools which refuse to take bullying seriously could face increasing legal action from the victims, a head teachers' leader has warned.

David Hart, General Secretary of the National Association of Head Teachers (NAHT), is urging his members to stamp out bulling by pupils and staff in their schools.

His warning came as the union published guidelines for anti-bullying policies to protect both pupils and teachers.

"All allegations of bullying have to be treated seriously because bullying can irrevocably damage the mental health of individuals," Mr Hart said.

"Ultimately, it could put the school at risk of a claim for damages."

"We live in an increasingly litigious society. There have been a number of high profile cases which have seriously affected the reputations of the schools concerned."

In October, North Yorkshire education authority paid �6,000 to the parents of 18-year-old John Carnell, after claiming the school had failed to prevent six years of bullying.

Last month, research suggested that despite the efforts in schools to counter the problem, almost one in four primary pupils in the UK are bullied.

Workplace bullying is also increasingly being acknowledged as a serious problem.

Last year, former deputy head teacher Anthony Ratcliffe won �100,000 in damages from Dyfed County Council after claiming he had been forced from his job at Sageston Primary School by the behaviour of its head, Joan Morris.

The NAHT's guidlines, which will be issued to members, stress that all bullying must be taken seriously and dealt with, and all complaints of bullying must be taken at face value.

"If the victim of bullying considers themselves bullied, then prima facie bullying has taken place and must be investigated," they say.

Mr Hart said employers had a duty under the 1974 Health and Safety at Work Act to ensure the health and safety of all those using their premises. That meant head teachers had a legal duty to prevent bullying, whether of staff or pupils.

Types of bullying

The NAHT's guidelines set out the range of behaviour which can constitute bullying:

• Physical bullying - pushing, kicking, hitting, pinching or any form of violence or threats
  
• Verbal bullying - name-calling, sarcasm, spreading rumours, persistent teasing
  
• Emotional bullying - tormenting, threatening ridicule, humiliation, exclusion from groups or activities
  
• Racist bullying - racial taunts, graffiti, gestures
  
• Sexual bullying - unwanted physical contact, abusive contact

The union also offers guidance on how to tell if pupils are being bullied.

Training for bullies

The guidelines also warn of the dangers of workplace bullying and warn heads to look out for resulting high rates of absenteeism and isolated members of staff.

Schools should have clear policies on bullying, the guidelines say, with clearly established means of complaint.

They say schools should be prepared to take all bullying problems seriously, investigate all incidents thoroughly and ensure that appropriate action is taken.

This could involve imposing sanctions and requiring bullies to apologise to their victims, and providing appropriate training for bullies in modifying their behaviour.