Simon Smith, the Essex chairman of the Professional Association of Teachers, is expected to tell the union’s annual conference in Harrogate that web-cams in schools could also give parents a better understanding of education.

“Web-cams would allow them to link up from their computers at work and home. They could simply log on, find their child in an appropriate location and find out what is happening. They would be able to help with homework more effectively and see how their child was behaving.”

Mr Smith, a design technology teacher at Sweyne Park school, Rayleigh, Essex, will propose a conference motion calling for parents to be given greater access to classrooms.

But, acknowledging the logistical difficulties of parents physically entering lessons, he plans to recommend the use of web-cams to achieve it.

Barry Hugill, spokesman for the civil liberties organisation Liberty, warned that the plan could become a “voyeurs’ charter”.

“What protection would there be to prevent people other than parents having access and why should parents be given the means to look at other people’s kids?” he said.

But Margaret Morrissey, spokeswoman for the National Confederation of Parent Teacher Associations, welcomed the idea providing the use of security codes ensured only parents logged on.

PAT members are also expected to discuss testing, the workload agreement and the pay and conditions of supply teachers.

Stephen Twigg, schools minister, is due to address the conference on Tuesday.