Supporters of the eco-activist Climate Camp, which occupied a main road in London, are among the 270 to have complained to the Independent Police Complaints Commission.
There is a long way to go before promoting and protecting human rights is central to police policy, training and operations
Joint Human Rights Committee
But the committee said the Climate Camp itself had also been "extremely unhelpful" because leaders had not provided the police with proper information about their plans.
"There is a case for considering the use of independent negotiators to facilitate dialogue between police and protests to overcome distrust and tensions," said the committee.
"Bodies such as the Independent Police Complaints Commission and HM Inspectorate of Constabulary may be able to assist in identifying and assisting such negotiators and there may be scope to draw on good practice in this area in Northern Ireland."
The committee added that while "kettling" tactics used to contain crowds were lawful, a blanket ban on individuals leaving an area was disproportionate.
Andrew Dismore MP, the committee's chairman, said: "While kettling may be a helpful tactic, it can trap peaceful protesters and innocent bystanders for hours.
"There must be clear safeguards in place to make sure containment is used only when necessary and proportionate."
The committee also said officers should be legally obliged to wear their identifying numbers, after a number of complaints during the G20 that officers did not have them on display.
Why would you trap passers-by with part-time protesters and the hardcore?
Sabina Frediani Liberty
Commander Bob Broadhurst, who is in charge of the Met's public order policing said, "thousands of protests pass off without notice due to planning with the organisers".
"This report, along with other reviews, provides us with a valuable framework to move forward our approach to public order policing," he said
"We are committed to working towards achieving constructive dialogue with protest groups, who traditionally haven't wished to talk with us. We seek that same commitment from them."
Sabina Frediani, campaigns co-ordinator at Liberty, said the police should "think again" about using "kettling" tactics.
She said: "Why would you trap passers-by with part-time protesters and the hardcore? This is a recipe for anxiety, anger and disaster."
The report comes as Sir Hugh Orde, Northern Ireland's former chief constable, takes over as the head of the Association of Chief Police Officers (Acpo). He has already called for human rights to be at the heart of modern policing.
Chief Constable Meredydd Hughes of Acpo said guidance on public order policing was being reviewed.
"Facilitating protest can be a difficult task for the police when balanced against the need to protect life and ensure that disorder does not break out," he said.
"It is clear that there are areas that can be improved and addressed as we review that guidance and we will study this report carefully as part of that process."
The graphic above shows how the police contain crowds of protesters, using London's Bank of England as an example. Protesters begin to gather from roads to the north and east, and are guided towards a central location by police.
A crowd of protesters forms outside the bank, as more join the demonstration from the surrounding roads. Police wearing high-visibility jackets begin to form a cordon around the crowd.
The police cordon has now entirely contained the crowd, but protesters can still enter if they so wish. Equally, people may leave the "kettle" through an exit point to the south or west, away from the main protest.
As the crowd grows and police perceive a threat, the cordon becomes a permanent "kettle" strengthened by riot police waiting in nearby vans. Nobody can enter or leave - possibly for hours.
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