Police are using CCTV images taken on university and college campuses, sometimes with the collusion of university authorities, to "spy" on student demonstrators as young as 16, it was claimed yesterday.

University lecturers are demanding an independent investigation into the "over zealous" use of surveillance techniques against students during the policing of demonstrations against fees rises and public spending cuts.

A motion tabled for the University and College Union's (UCU) conference this weekend condemns what it terms attempts to "criminalise protest" through "state surveillance of higher education and further education institutions for elicting intelligence regarding protest activities".

Cases include the arrest of four students at University College London (UCL) after the university authorities handed over CCTV footage of them chalking the walls of one of its buildings during a student occupation.

In addition, 16 and 17-year-olds from Barnsley College were questioned by police who already knew their names after they had returned to the town following a mass demonstration against fees rises in London.

In the UCL case, Scotland Yard confirmed that two 20-year-old male students had been arrested on 10 May as a result of an investigation into reports of criminal damage to a building. They have both been bailed until next month pending further enquiries.

The UCL said two more students had been arrested three days later. The four were among five targeted for arrest following graffiti damage at the time of the occupation.

A spokeswoman for the university added: "UCL reported the damage... as a police matter. UCL handed over CCTV that identified the persons involved at the time of the damage."

She said this had been done as part of an attempt to co-operate with a request for personal data from the police – made to the university's data protection manager.

In the Barnsley case, Dave Gibson, UCU branch secretary at Barnsley College, said he was "alarmed" that police who had questioned the students already knew their names without being told who they were.

"It is quite worrying for a 16 or 17-year-old," he added. "Clearly there was some kind of surveillance going on. From their questions, they had certainly filmed them and had footage of that."

The youngsters had – with the permission of their college – joined lecturers on the first major demonstration against the plans to raise student fees to up to £9,000 a year when protesters broke into the Conservative party headquarters at Millbank.

They had then returned to London for a second demonstration timed to coincide with the debate in Parliament which approved the fees rises. "I think there is a feeling and suspicion around that there has been a change in police attitudes since the first demonstration in November," said Mr Gibson.

"It was as if the police were saying 'We got caught out on 10 November and it won't happen again'. I think, since then, they have been over-zealous in their activities."

At a demonstration last week in Barnsley, where students were protesting about the threat to sack 300 lecturers at the college, an array of police vehicles flanked the demonstrators throughout despite a lack of violence.

The conference motion is also critical of police "kettling" tactics which have seen student protesters held in Parliament Square and Westminster Bridge long into the night.