School managers show an alarming degree of complacency on school security even after Dunblane, a survey of more than 1,000 schools has shown.

The National Association of Schoolmasters Union of Women Teachers found that between a third and half of all schools had no procedure for recording and reporting violent incidents; only half of nursery schools and a third of secondaries had comprehensively assessed their security arrangements. Forty per cent of all schools had no safety measures at all.

Yet there had been a disturbing increase in the use of weapons to threaten or attack staff, including air pistols, replica firearms, a meat cleaver and chemical sprays. More than two-thirds of union representatives in schools believed that violence had increased in the past three years, with an alarming 10 per cent saying that violence was the issue to which they gave top priority.

“If this figure is at all representative, nearly one in every 10 UK schools is in major difficulty,” says the report. “It is teachers, not school governors, local authority officials or politicians who face the threat of actual or potential violence on a daily basis.”

The union has collated more than 60 pages of accounts of incidents such as drunken youths vandalising lavatories; and, most worrying, intruders who appear for no apparent reason, but are usually under the influence of alcohol or drugs, so it is difficult to know how they will react if challenged.

“How is a teacher supposed to react to an intruder who claims, in one reported incident, to be a ‘friend of Thomas Hamilton’?” asks the report.

In addition to threats from outsiders, union members reported a range of attacks by pupils on other children and teachers. One boy punched a teacher in the stomach for ruling against him at football; four pupils were expelled for bringing knives into school; pupils threw stones through a window where a meeting was being held; and a boy was excluded for carrying an 8-inch knife hidden in his sock.

Parental violence is a bigger cause of anxiety for junior and nursery schools than for secondaries, although most of it is verbal, rather than physical abuse. One teacher reported: “Parents are more aggressive in their attitude towards teachers, unreasonably defensive of their own child’s behaviour and occasionally unaccepting of the teacher’s version of an event - the overall change in attitude is threatening.”

The report said that a small group of school managers had taken effective steps to deal with security as far as resources allowed with a larger group seen as well-meaning but ineffective. “The third group exhibits a degree of complacency which is little short of alarming; this group has no idea of the nature and scope of the problem, or seeks to minimise, trivialise or otherwise sweep it under the carpet.”

NASUWT has issued an action plan which calls for heads to support class teachers, and an acceptance that teachers should teach, not patrol the neighbourhood sorting out trouble.

It also calls for the removal of the OFSTED criterion under which it can label schools as failing if the exclusion rate is too high. It wants to prevent local authority appeal panels, sending back pupils whose presence teachers find unacceptable.

The union wants to halt the closure of schools for children with emotional and behavioural difficulties. It also calls for more pupil referral units and more security cameras and panic alarms.