Extinction Rebellion activists defied police orders to clear their protest sites in central London by gluing themselves to buildings and vehicles.
More than 212 people were arrested on the second day of the demonstration, bringing the total to 531 by Tuesday evening.
“We believes that this action is necessary in order to prevent the demonstrations from causing serious disruption to the community,” the force said in a statement.
But while encampments on Lambeth and Westminster Bridges were cleared, the protests continued at several other key locations.
Several people glued themselves to the Department for Education building, where young activists gathered outside to demand they be “taught the truth”.
Another activist attached himself to the underside of a lorry outside the Home Office in Marsham Street, as the ”Red Rebel” protesters dressed in crimson stood face to face with police officers.
Police attempted to clear tents and other equipment at the sites in Whitehall and Downing Street but Extinction Rebellion indicated their members were “locked on” and prepared to go to jail.
“We’re here to stay,” declared one group of “Northern rebels” from Leeds after holding a people’s assembly in Millbank to decide on their next move.
Footage also emerged of a man, described as “grandfather Tony, 74, from Cambridge”, sounding a fire alarm to trigger the evacuation of the Oil & Money conference at a five-star hotel in London’s Park Lane.
Meanwhile, at the Houses of Parliament, activists “reforested” parliament with 1,000 potted native trees, before handing individually labelled trees to each MP.
A few yards away at Westminster tube station, protesters sought to highlight homelessness in central London by holding a sit-in and attempting to raise the issue with passing MPs, including Labour’s Keir Starmer.
Extinction Rebellion have also announced a “Hong Kong-style” shutdown of London City airport.
The climate activists plan to occupy the departure and arrival lounges for three days from 9am on Thursday. If that fails the group says it will occupy the DLR station and the road outside the terminal.
In a message announcing the protest, the group said: “Our biggest action of the rebellion starts in less than 48 hours.”
Scotland Yard, after receiving criticism for failing to prevent protesters from blocking roads in the capital, said it was taking time to clear people who had glued or locked themselves together.
“Clearing protest sites can be really difficult for the police service,” said deputy assistant commissioner Laurence Taylor. “We have to manage that in a balanced and measured way and do so while recognising the wider risks to London so that people can go about their daily lives.”
One of the protesters who said they were willing to be arrested was a former Metropolitan Police detective sergeant, John Curran, who was detained during the protests in April.
He said the police “probably have better things to be doing”, but said the responsibility for the situation “must lie with the government”. He added: “Take action and we won’t have to be here. Take action: that’s the only demand that I have.”
Additional reporting by Press Association
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