Teachers' leaders have demanded an end to the policy of stationing police officers at Scottish schools.

One third of Scotland's 32 local authorities have already sanctioned the use of so-called "campus cops" as a means of combating indiscipline, including East Renfrewshire, North Lanarkshire, South Ayrshire, and Fife.

Officials believe the practice has already resulted in declining levels of vandalism, street drinking and assaults - and also allows officers to crack down on the activity of gangs.

However, Helen Connor, vice-president of the Educational Institute of Scotland, attacked the schemes, which she said were trying to turn teachers into informers.

She told the annual general meeting of the EIS in Dundee that police officers should be operating in the community, rather than schools, and criticised their introduction in some local authorities without proper consultation.

"When we asked the local authority why this had happened and why the schools have been chosen, the answer they gave was that communities around the schools had particular difficulties with the 15-17 age group," she told the meeting on Saturday.

"Why then, I ask, were the police officers put into the schools and not extra officers put into the community?

"They were looking for intelligence gathering, they wanted staff in school to tell them about what the young people were doing.

"That's not why I came into teaching. I did not think I would ever see, in Scotland, police officers in schools."

In a motion to the meeting, which was passed by delegates, Ms Connor called for a new guidance to be drawn up to ensure that, where officers were stationed in schools, their roles and responsibilities were clearly defined.

"I don't think there should be campus police officers at all. I think these people should be in the community looking at the problems of society, but if we do have them we should have them with an agreed protocol."

In all there are currently 44 campus officers across Scotland, 35 in Strathclyde, two in Lothian and Borders, one in Central and one in Dumfries and Galloway. Fife has five campus officers, two based at a single school, two covering two schools each and one covering three schools.

Essentially community police officers, they are usually based full-time within a single secondary school which has been selected by local divisional commanders and education authorities.

A national evaluation of the campus officer role within schools is expected to be carried out by the Scottish Government later this year.

Detective Chief Superintendent John Carnochan, head of the Violence Reduction Unit, which has championed the scheme, said: "Campus officers perform a unique role - they're not there to police classrooms, they're there to build stronger community relationships and act as positive role models for children who may lack such a figure in their lives.

"The Scottish Government has agreed to perform a national evaluation of the campus officer within schools, but a preliminary report on the experiences of two schools in 2006 highlighted that they feel having a campus officer had been beneficial both to the school and its pupils and to the community at large."

The VRU also cited the example of Scotland's longest serving campus officer, PC Geoff Smith, who has been based at St Mungo's Academy in Glasgow's east end for the past three years. Since then levels of truanting fell in the school, as did levels of graffiti and vandalism.

But an East Renfrewshire Council spokesman said the authority "repudiates entirely" claims made by the EIS and said the authority hoped to deploy campus police in all its secondary schools as and when funding became available.

Glasgow's SNP opposition in February lobbied for a campus cop in every secondary school in the city, attempting to force it on to the authority's budget priorities for 2008-2009. The group's leader, Cllr John Mason, yesterday maintained his proposal would have been a welcome addition to the city's schools.

He said: "Schools are part of the community and not little castles and if the cops are in schools they are performing a community role. Many of the staff at Bannerman High, which is in my ward, have had nothing but very, very positive comments to make about their campus cop."

Patrick Cullen, an EIS delegate from North Lanarkshire, said he accepted campus cops could make a valuable contribution to pastoral care, but said they should never be enforcers of school discipline.