At least 16 people were arrested on public order offences in Friday's mob violence which left 46 people in hospital including six police officers and two demonstrators. CCTV footage may reveal the identities of other suspects.
Police said the 4,000 marchers turned from peaceful protest to riot when the demonstration was hi-jacked by anarchists, intent on organised violence, who targeted unprotected police.
City of London officers said the campaigners had a track record of extreme violence and had refused to co-operate with police in route-planning the "Carnival Against Capitalism" march. Protesters say police inflamed the situation by using officers in riot gear. In the worst street violence since the poll tax riots in 1990, police were attacked with bricks and concrete blocks. A Daimler and a Mercedes were set alight and protesters used scaffolding poles to smash into banks and trading firms. One motorist was dragged from his car and doused in bleach.
The protests are understood to have been publicised through the Internet by an umbrella movement called J18, for June 18, timed to coincide with the Group of Eight economic summit in Cologne, attended by Prime Minister Tony Blair.
Separate J18 groups, including environmentalists Reclaim The Streets and Jubilee 2000, were protesting against capitalism, saying it is destroying the environment and forcing millions into poverty.
James Hart, assistant commissioner for City of London police, said between 5,000 and 10,000 people had been expected and his 800 officers were briefed with units from the Metropolitan and British Transport Police. The protest started peacefully, with a few hundred marchers in the City but by early afternoon the numbers swelled to about 4,000, gathering at Liverpool Street Station.
"Clearly these people came to the City yesterday with the full intention of causing mayhem," said Mr Hart. "The situation changed at Liverpool Street when a very carefully organised crowd split into four parts, and aimed their violence at unprotected police officers. We tried to remove the focus of the violence, which at that time was the police and thought ... the violence would end, but it did not."
Lord Levene, Lord Mayor of the City of London, dubbed the offenders "terrorists". He said: "If you have people throwing bricks and scaffolding then the police have to have protection in the form of riot gear. Usually people holding demonstrations talk to the police before. In this case they refused."
But one protester, Mark Lines, told BBC Radio4's Today programme: "Police in full riot gear and looking extremely offensive charged at the demonstrators and started attacking them."
Ann Widdecombe, shadow home secretary, called for an investigation. "Every year there are hundreds of demonstrations in London and there have been emotional ones which the police have controlled. In this case something went wrong and we have to find out what," she said.
"There has been a severe drop in the police force which is something Jack Straw [the Home Secretary] has to take responsibility for. But it is no good blaming the police if individuals are causing trouble. You cannot describe this as a protest. It was about violence."