The Lib Dems released images of policing at the Climate Camp
Police have been accused of using sleep-deprivation to intimidate climate change protesters in Kent.
Activists at last year's Climate Camp gathering at Kingsnorth were woken up by The Clash's I Fought The Law and the Hi-de-Hi! theme, a report claimed.
The Liberal Democrats, who presented the study to Parliament, renewed their calls for an inquiry into the policing.
Kent Police said the team responsible for playing loud music inappropriately was from another police force.
About 1,000 demonstrators attended the camp in August to protest against plans for a new coal-fired power station at Kingsnorth.
The Lib Dems said policing was disproportionate and outrageous.
"The camp started with searches carried out on a massive scale - in my view all unlawful," said Francis Wright, a co-author of the report and lawyer for Camp for Climate Action.
"Everybody was searched, essentially under the 'sus' law for which you are supposed to have reasonable grounds to suspect that individual.
"It was stereotyping on a massive scale. We were all treated as criminals."
The report claims psychological operations were used by police, including frequent dawn raids, low-flying helicopters at night and the unnecessary massing of police officers and vans.
Legal observers at the demonstration were denied access to individuals requesting their support, the report claimed.
Officers were also accused of using threatening behaviour to compile a systematic database of the names and addresses of attendees.
"It is a question of proportionality," said Lib Dem justice spokesman David Howarth.
"We got a police presence of more police officers than protesters.
"All these police officers had to come from somewhere else and they weren't doing their job of preventing crime elsewhere."
Police searched people entering the camp site near the power station
Responding to previous accusations of disproportionate policing measures, ministers had claimed that 70 officers were injured.
It later turned out, however, that no injuries were sustained in clashes with demonstrators, with the figure including such incidents as a suspected wasp sting and sunstroke.
Kent Police said in a statement: "We are aware of one occasion when officers played music loudly and inappropriately.
"The police team responsible for this was quickly identified, and immediately sent back to their home force."
The statement added: "The policing operation around Climate Camp was large, complex, arranged at short notice and without the co-operation of protest organisers.
"It was an illegal mass trespass without the consent of the landowner.
"The stated intention from the outset was to break into the power station, putting lives and the power supply to 300,000 residents at risk.
"The police operation was very successful in preventing such criminality and harm while, at the same time, enabling a protest around an issue of genuine public concern to go ahead."
There are fresh calls for an immediate inquiry into the policing of the Kingsnorth Climate Camp