Environmental protesters are hoping to "shut down" London and force the Government's hand on climate change on Monday.
Some activists, described as earth marchers, have been making their way to the city for weeks from various parts of the UK for what is described as an “International Rebellion”.
From Monday, thousands of people will meet at five busy locations in the city, peacefully blocking traffic and kicking off a “festival” of action - including people’s assemblies, performances, talks, workshops and food, campaign group Extinction Rebellion said.
People will take to the streets at Marble Arch, Oxford Circus, Waterloo Bridge, Piccadilly Circus and Parliament Square in a bid to cause disruption and force the Government to act.
Campaigners said participants could go to training sessions and briefings “to make sure everyone is prepared for the mass civil disobedience to follow”, warning that while the movement is a peaceful one, there is always the possibility of arrest.
Demonstrators are encouraged to camp overnight in Hyde Park into Monday, where they can “come together, form relationships, consolidate our plans, and gear up for the days ahead”.
But they have been warned they could be breaking the law by setting up camp, as doing so without permission is an offence under Royal Parks legislation.
A spokeswoman for The Royal Parks said Extinction Rebellion had not asked for permission to begin the protest in the park and that camping is not allowed.
She said: “We never allow camping in the parks for reasons of safety, security, lack of welfare facilities and the impact it has on the park. It also removes public space from other park visitors.
“Those camping in the parks are breaking the law. Enforcement of the park regulations is a matter for the Metropolitan Police.”
Police said their operational response “would be dependent on what if any other issues might be ongoing at the time”.
Scotland Yard said they have “appropriate policing plans” in place and that officers will be used from across the force “to support the public order operation during the coming weeks”.
They added: “We will always provide a proportionate policing plan to balance the right to a peaceful protest, while ensuring that disruption to communities is kept to a minimum."
April Stewart, who travelled from Carmarthenshire in Wales for the demonstration, said the prospect of being arrested “doesn’t phase me”.
The 52-year-old artist said: “I am not someone who is normally drawn to civil disobedience. I am moved by this cause, by this moment in time that we have to make a difference.”
Asked if she thought the Government will take notice, she said: “I guess that depends how effective we can be in shutting down the city.
“It has to inconvenience them enough, it has to inconvenience the financial system, it has to inconvenience the tourist industry, it has to inconvenience the Government enough to recognise that they need to engage with this.”
She said the disruption would mimic disruption they expect will be caused in the future by the effects of climate change and the destruction of the ecosystem.
Police advised people travelling around London in the coming days to allow extra time for their journey in the event of road closures and general disruption.