Police will on Thursday be accused of using "unjustified" violence against children who went on demonstrations against tuition fee rises.

Police officers are alleged to have used batons and riot shields to strike the mainly peaceful protesters, many of whom were aged under 16.

The accusation is levelled by three academics who have extensively studied the police's handling of two demonstrations in Brighton in November. Police deny that their tactics were heavy handed and said the researchers did not give them a chance to contribute to the study.

The academics recorded instances of protesters "being struck with hands, batons, and shields, being kicked, pushed to the ground, thrown, placed in headlocks, threatened by dogs … yet there are no recorded incidents of protesters harming or threatening members of the public, or other protesters".

"The level of violence used by the police against demonstrators … was disproportionate and unjustified, given the relatively peaceful nature of the protest," they say in their report, which they will make public on Thursday.

Many young people from schools and universities demonstrated in the centre of Brighton against government plans to raise university fees and cut education funding on 24 and 30 November last year. More than 2,500 demonstrated in the first and at least 1,500 in the second, according to the academics.

The Brighton demonstrations were part of last autumn's wave of protests in which thousands of students and school pupils walked out of class, marched, and occupied buildings around the country.

The academics, who are all historians from Sussex and Brighton Universities, based their conclusions on 35 video films, 230 photographs, 20 accounts by protesters, and posts on Twitter. Their report has not been peer reviewed.

The policing of the demonstrations "suppressed the political expression of school, college and university student communities and served to criminalise local forms of political protest … children were mistreated by the police," conclude Dr Thomas Akehurst, Dr Louise Purbrick and Dr Lucy Robinson.

The academics are particularly critical about Sussex police's use of "kettling", in which protesters are held against their will behind a cordon of police officers for considerable periods.

The academics question the legality of the six "kettles" which Sussex police imposed on the protesters during the two demonstrations.

"It is estimated that 1,400 people were kettled, of whom the majority were under 18 years of age and a large proportion were under 16 years old."

They say "kettling" was used as a standard police response to demonstrations, in apparent contravention of police guidelines which advise that the tactic should be limited to preventing disorderly or violent behaviour.

They allege that "kettling" appeared to be used "as a form of collective punishment" against dwindling numbers of protesters at the end of the demonstrations.

They also criticised police for making the young protesters give their names and addresses under antisocial behaviour legislation as a condition of release from a kettle.

In response to the allegations, Chief Superintendent Graham Bartlett, Brighton and Hove City police commander said: "We take very seriously our legal and moral duties to carefully balance people's right to peacefully protest with our duty to protect the public. We are extremely disappointed that the same balance has not been applied to the undertaking of this research. Despite our early offer to participate, the research team has not even acknowledged it, let alone taken it up."

"We have serious reservations about the methodology and academic rigour, given its quick publication and the researchers' reluctance to engage with a key party to the events."