Hundreds attended the demonstration in Parliament Square yesterday (August 9) organised by Defend Our Juries.
Metropolitan Police said that they arrested 466 people on suspicion of showing support for Palestine Action, which was recently proscribed as a terrorist organisation.
The force added that there were eight further arrests relating to other alleged offences.
Five people were arrested on suspicion of assaulting a police officer. None were seriously injured.
The Met said the detained protesters were taken to prisoner processing points in the Westminster area, and those whose details could be confirmed were bailed, with conditions not to attend any further protest in support of Palestine Action.
Those whose details were refused, or could not be verified, were taken to custody suites across London.
Charity Amnesty International described the mass arrests under UK terrorism law as “deeply concerning”.
Sacha Deshmukh, chief executive of Amnesty International UK, said: “The protesters in Parliament Square were not inciting violence and it is entirely disproportionate to the point of absurdity to be treating them as terrorists.
“We have long criticised UK terrorism law for being excessively broad and vaguely worded and a threat to freedom of expression. These arrests demonstrate that our concerns were justified.”
Home Secretary Yvette Cooper thanked police in London and across the country for their work to ensure peaceful protests, and officers’ “continued dedication in responding to support for a proscribed organisation”.
Some reporting by PA.
