Parents believe police officers are increasingly being located on school sites because teachers have lost control, a survey has found.
The research concluded that parents think Safer School Partnerships (SSPs) - which are growing in number throughout England - are needed to bring back authority and respect and weed out unruly children.
Around 20 per cent of primaries and 45 per cent of secondaries in England are involved in SSPs or other formal arrangements with the police. While the scheme sees police working on school sites, teachers still retain overall responsibility for discipline.
The formal aim is for children to get to know their local officer so that community relations between families and the police improve.
But the researchers - commissioned by the Department for Children, Schools and Families - found that the Government needs to counter the perception that SSPs are being introduced to deal with bad pupils or failing schools.
Staff from research company Sherbert met with parents and children from schools around the country - with and without dedicated police officers on site - to ask for their views on SSPs.
The majority of survey participants expressed relief that something was being done to make schools safer.
"They imagined the role of SSP officers was to weed out unruly pupils so children could learn in a safe and comfortable environment," the researchers said.
"All parents in this sample felt sadness and concern that it had come to this - ie that police were necessary in schools. They recalled their school days when they felt there was a clear power difference between teachers and pupils and the police had no presence in schools."?
Some parents struggled to see what role police officers could play in schools which were already "safe". The researchers recommend that police tailor their activities more to the location and needs of pupils, teachers and the local community.
Pupils said they wanted the officer to be friendly, not focused on enforcing school rules and to avoid wearing uniform. They suggested that police wore the school badge to signal they were "on the same side" as them.
Graham Robb, a director of the Youth Justice Board, which runs SSPs, said teachers and police now needed to explain the role of the various parties.
"What matters is making sure that every school with an SSP is clear what it is for. This means explaining it to staff pupils, parents and the community in ways which reassure that the purpose is to prevent harm," said Mr Robb, a former headteacher who set up one of the first SSPs.
"We also need to ensure a school with an SSP is seen as one sign of school which is being open in working with its community."