Sussex Police police used unjustified violence during protests against tuition fee rises in Brighton, a report by academics has found.
Three university academics have published a report into the policing of two marches, on November 24 and 30.
The study found officers used excessive force and beat non-violent protesters with batons - some as young as 14.
Sussex Police has defended its response and said researchers did not allow them to contribute properly to the study.
The academics, from the universities of Brighton and Sussex, scrutinised police tactics of the protests held to oppose government plans to raise the cost of university tuition fees.
'Thrown and punched'
They interviewed pupils and students who took part in the demonstrations against tuition fees, but did not conduct any face-to-face interviews with police.
Co-author Dr Tom Akehurst said the aim was to catalogue the experiences of people involved in the protests, particularly young people.
He said a separate study involving the police was being carried out.
The report found that "many protesters were pushed by police officers and some were pulled, thrown, hit and punched".
It also found that "the level of violence used by police against demonstrators was disproportionate and unjustified, given the relatively peaceful nature of the protest".
Police estimated about 3,000 people took part in the first protest.
The report said the majority of those were young people, many school-aged children.
The academics took first-hand experiences and examined of hundreds of photographs and films of the protests to collate the report, as well as using posts on Twitter.
Sussex Police's use of "kettling", whereby protesters are kept behind a cordon against their will for considerable periods, was also criticised in the report.
It said that officers established six kettles and that 1,400 people overall were involved, the majority of whom were under 18.
The report, by Dr Akehurst, Dr Louise Purbrick and Dr Lucy Robinson, also accuses the police of using violence or the threat of violence to impose and maintain the kettles.
Dr Purbrick said: "Testimony shows the use of violence and kettling against quite young children, and reveals police insisting children be filmed as a condition of their release."
Chief Supt 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."