Police are being called to schools hundreds of times a week
The police were called to violent incidents in schools in England more than 7,000 times last year, according to figures from the Conservatives.
Police forces were asked how often they were called to "school premises for an attempted or actual violent crime".
The survey was based on responses from 25 of the 39 police forces in England.
Head teachers' leader John Dunford said the survey was "scaremongering" and added that schools were often havens of safety in troubled communities.
But Shadow Children's Secretary Michael Gove said the figures on police calls showed that schools did not have enough power to "nip discipline problems in the bud".
"The number of violent incidents in schools that lead to police being called is very worrying," said Mr Gove.
Michael Gove 'The violence and behaviour problem is running out of control'
The figures published by the Conservatives were obtained under Freedom of Information requests - with an overall total of 7,311.
There are wide variations between different parts of the country. Police in Warwickshire recorded 73 call outs over violent incidents in school, Merseyside 141, Kent 425 and the Metropolitan Police area 2,698.
How the figures were gathered varies between forces. For example, the figure for the Metropolitian Police applies to "educational establishments" rather than only schools, and the figure for Kent includes incidents in the "vicinity of schools".
Thames Valley had the second highest figure with 697 call outs, but said that differences in how the figures were compiled meant that comparisons were not valid.
"There are 175 state secondary schools in Thames Valley, attended by 161,000 pupils. The statistics represent an average of four violent crimes per school per year," said a spokesman.
What the figures do not show is whether this is a small number of schools repeatedly calling the police to tackle incidents or a more widespread changing pattern in which the police are being called occasionally to large numbers of schools.
Nor is there any breakdown of whether the incidents involved pupils or parents, or ex-pupils returning to cause trouble.
But this provides a snapshot suggesting that police are being called to schools hundreds of times each week and that they are carrying out interventions that were once the responsibility of teachers.
Dr Dunford, general secretary of the Association of School and College Leaders, said schools were more likely to call the police than in the past.
He said this reflected a closer working relationship between schools and the police which means that schools are more likely to use police assistance.
"Parents and pupils should not be scared by these stories - they should be reassured that, when violence does occur in school, it is dealt with quickly and firmly," said Dr Dunford.
He added: "Many of these incidents involve young people who are not pupils at the school trespassing on school premises and causing trouble. School sites are often very open places."
We want schools to work closely with the police as part of the Safer School Partnerships and to take a hard line when dealing with poor behavioure
And Chris Keates, head of the Nasuwt teachers' union, said the figures could be a sign that teachers were more willing to report such violent incidents to the police.
But she urged caution with the statistics, as they do not show differences in how local police forces respond to such school incidents or whether the figures relate to pupil misbehaviour or to other problems such as intruders.
She also rejected the Conservatives' conclusion that schools lack sufficient powers to tackle misbehaviour.
"In recent years schools have had increasing powers devolved to them to tackle pupil indiscipline. The real issue of concern is that still too many fail to use them."
Martin Johnson of the ATL teachers' union said the figures on police being called to schools reflected the worries of classroom violence.
"In February, 29% of teachers told us they have faced physical aggression from a pupil, and over 90% said pupils have been excluded from their school for behavioural problems."
Mr Johnson also said that more than two-thirds of teachers said "pupil behaviour was worse than two years ago".
As well as the police being called by schools for assistance, there are 450 schools in England which have dedicated police officers, either based in the school or shared between a group of schools.
A spokeswoman for the Association of Chief Police Officers said the "police service works closely with schools in the prevention of crime and anti-social behaviour".
The Department for Children, Schools and Families also asserted the value of schools and police working together.
"We want schools to work closely with the police as part of the Safer School Partnerships and to take a hard line when dealing with poor behaviour," said a spokeswoman.
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