A review into G20 protests in London in April has concluded the police's public order tactics were inadequate. However, the report says the operation itself was highly effective.
The report by Her Majesty's Inspectorate of Constabulary (HMIC) was commissioned by London's police chief Sir Paul Stephenson after concern about police tactics and accusations of excessive violence by some officers.
The concerns included the death of newspaper seller Ian Tomlinson, 47, who died after he got caught up in a demonstration outside the Bank of England on 1 April.
Days later, video footage emerged of a police officer apparently pushing him to the ground shortly before he died.
The Independent Police Complaints Commission has since received hundreds of complaints about police handling of the demonstrations and a number of officers have been suspended pending investigations.
The 150-year-old HMIC is independent of the Home Office and the police service.
Its report said that in "some significant respects", police had planned and responded well to the challenging demands of policing the protests and providing security for the summit of world leaders.
However, it said there were genuine concerns about containment tactics - or "kettling" - the use of force to disperse peaceful protesters, the identification of officers and communication before, during and after demonstrations.
It said officers had been given confusing instructions on how to carry out the kettling, and that police were more concerned about whether a protest was illegal than facilitating peaceful demonstrations.
Both the guidelines from the Association of Chief Police Officers on policing protests and the Met's public order training were described as "inadequate", the report said.
Metropolitan Police (MPS) Assistant Commissioner Chris Allison said the force was always seeking to learn.
"This independent review provides us with a sound framework upon which we can move forward," he said.
"Whilst containment is the most effective tactic that we currently have, to deal with violence and disorder in these types of situation, the MPS has always acknowledged that there are challenges associated with it."