TEACHERS are alarmed that surveillance cameras are being fitted in NSW classrooms, citing privacy concerns and fears of misuse.

Some schools already have closed-circuit television cameras in outdoor areas, including playgrounds, but more are eager to install them inside classrooms and corridors.

NSW Teachers Federation senior vice-president Bob Lipscombe said a growing number of teachers had spoken out in recent months, worried that the footage could be used inappropriately and that they would be filmed throughout their working day.

"They are concerned about its improper use and that it may be taken out of context," Mr Lipscombe said.

An increasing number of schools are keen to install the video surveillance, particularly around computer rooms, in an attempt to protect expensive equipment.

With many different subjects being taught in the computer rooms throughout the school day, the installation of security cameras is an issue that could potentially affect many teachers, Mr Lipscombe said.

"It could be an English lesson using the web," he said.

Some schools favour a CCTV system as cheaper than securing a room with bars and an alarm

Mr Lipscombe said the privacy of students in the rooms was another consideration.

One solution could be to run a camera system that switches on only after hours or when the rooms are unattended.

He said the federation was not against the use of CCTV systems as long as they were used appropriately and with proper consent.

More than 50 schools already have some type of camera surveillance in place, NSW Department of Education figures show.

"Not all schools are suitable for CCTV cameras, due to the size and physical layout of the school," a department spokesman said.

"Where this and legal or privacy issues are raised, a school is recommended to use another effective security measure or a combination of measures."

The spokesman said: "The footage from CCTV cameras is confidential and is released to the police to help with their investigations in the case of criminal activity impacting on the school."

Teachers have also expressed concern about an increasing tendency for students to film them using mobile phones and posting the footage on interactive websites.