Almost 900 demonstrators were arrested at a Central London rally protesting against the banning of Palestine Action as a terror group, the Metropolitan Police has said.
An estimated 1,500 took part in the protest in Parliament Square, Westminster, on Saturday and the force condemned the "intolerable" abuse it claims its officers suffered.
But organisers, campaign group Defend Our Juries (DOJ), insisted the rally was "the picture of peaceful protest" and called on new Home Secretary Shabana Mahmood to drop the "unenforceable" ban.
A total of 890 people were arrested, with 857 arrests made for showing support for a proscribed group, while 33 people were arrested for assaulting police officers and other public order offences.
Deputy Assistant Commissioner Claire Smart said: "The violence we encountered during the operation was co-ordinated and carried out by a group of people, many wearing masks to conceal their identity, intent on creating as much disorder as possible. Many of those individuals have now been arrested and we have begun securing charges.
"The contrast between this demonstration and the other protests we policed yesterday, including the Palestine Coalition march attended by around 20,000 people, was stark.
"You can express your support for a cause without committing an offence under the Terrorism Act or descending into violence and disorder, and many thousands of people do that in London every week.
"We have a duty to enforce the law without fear or favour. If you advertise that you are intending to commit a crime, we have no option but to respond accordingly."
On Sunday, Defence Secretary John Healey said Ms Mahmood will be "just as tough" on Palestine Action as her Home Office predecessor, Yvette Cooper, who moved to the Foreign Office as part of Sir Keir Starmer's wide-ranging Cabinet reshuffle on Friday.
Asked whether there would be a shift in Government policy on the group, Mr Healey said: "I expect Shabana Mahmood to be just as tough as Yvette Cooper and I expect her to defend the decision the Government's taken on Palestine Action, because of what some of its members are responsible for and were planning."
"If we want to avoid a two-tier policing and justice system in this country, when people break the law, there have to be consequences," he told Sky News's Sunday Morning With Trevor Phillips.
"That's what was happening yesterday, and I, we, almost everybody shares the agony when we see the images from Gaza, the anguish when we see the man-made starvation, and for people who want to voice their concern and protest, I applaud them.
"But that does not require them to link it to support for Palestine Action, a proscribed group."
Palestine Action was banned as a terror organisation in July after the group claimed responsibility for an action in which two Voyager planes were damaged at RAF Brize Norton on June 20.
The Home Office is set to appeal against the High Court ruling allowing Palestine Action's co-founder, Huda Ammori, to proceed with a legal challenge against the Government over the group's ban.
Ms Ammori took legal action against the department over then-home secretary Yvette Cooper's decision to proscribe the group under anti-terror laws, which made membership of, or support for, the direct action group a criminal offence punishable by up to 14 years in prison.