Extinction Rebellion activists are continuing protests despite a London-wide ban by police.
The group says it has taken initial steps towards a judicial review of the ban. Lawyers and politicians have also criticised the move.
Meanwhile climate change protesters targeted the Department for Transport and MI5 on Tuesday morning.
A government spokeswoman said protests “should not disrupt people’s day-to-day lives”.
Extinction Rebellion’s co-founder, Gail Bradbrook, was arrested after climbing on to the entrance of the Department for Transport on Tuesday morning. Police also cleared further protesters from outside the building.
Activists have also been arrested on Millbank outside MI5’s headquarters, where a small group had gathered. Two men briefly sat in the middle of the road before being moved by officers.
On Monday evening, the Metropolitan Police began clearing protesters from Trafalgar Square following the announcement of a ban on the protests.
Under Section 14 of the Public Order Act, the force had imposed conditions requiring activists to stop their protests in central London by 21:00 BST on 14 October or risk arrest.
The Metropolitan Police said that the ban was imposed after “continued breaches” of a condition limiting the demonstration to Trafalgar Square.
Extinction Rebellion said it had taken the “first steps” towards a judicial review of the Met’s “disproportionate and unprecedented attempt to curtail peaceful protest”.
“Our lawyers have delivered a ‘Letter before Action’ to the Met and asked for an immediate response,” a statement read.
Tobias Garnett, a human rights lawyer working for the movement, said the letter warned police to withdraw the order.
He said the campaign group had given the police a deadline of 1430 BST to respond, or it would file a claim in the High Court.
“We will be looking for an expedited hearing either today or tomorrow morning,” he added.
Speaking to the Victoria Derbyshire programme, Extinction Rebellion campaigner and former Met Police officer Paul Stephens said: “Police are being really sloppy with the law, and it won’t stand up in court.”
Mayor of London Sadiq Khan has said he is “seeking further information” about the decision to impose the ban and why it was necessary.
“I believe the right to peaceful and lawful protest must always be upheld,” he said.
A spokeswoman for the government said the UK was “already taking world-leading action to combat climate change”.
The statement added: “While we share people’s concerns about global warming, and respect the right to peaceful protest, it should not disrupt people’s day-to-day lives.”
Home Secretary Priti Patel tweeted that “supporting our [police] is vital” and accused the Labour Party of supporting “law breakers”.
‘Overreach of powers’
Meanwhile, lawyers have also questioned whether the ban by police is legal.
Anti-Brexit barrister Jo Maugham QC said the move was “a huge overreach” of police powers, while human rights lawyer Adam Wagner described it as “draconian and extremely heavy-handed”.
Mr Wagner added in a tweet: “We have a right to free speech under article 10 and to free assembly under article 11 of the (annex to the) Human Rights Act. These can only be interfered with if the interference is lawful and proportionate. I think the police may have gone too far here.”
Shadow home secretary Diane Abbott tweeted: “This ban is completely contrary to Britain’s long-held traditions of policing by consent, freedom of speech, and the right to protest.”
Allan Hogarth, of Amnesty International, issued a statement saying the ban was “an unlawful restriction on the rights to freedom of expression and peaceful assembly”.
A number of demonstrations have been staged across the capital by Extinction Rebellion, which is calling on the government to do more to tackle climate change.
The protests were due to last two weeks and have led to more than 1,400 arrests.
The Met said there had been 1,457 arrests by 08:45 BST on Tuesday, in connection with the nine days of Extinction Rebellion protests in London.
Last week, the Home Office confirmed to BBC News that it was reviewing police powers around protests in response to recent demonstrations.
What are the rules around protests?
Police have the powers to ban a protest under the Public Order Act 1986, if a senior officer has reasonable belief that it may cause “serious disruption to the life of the community”.
Police are also under a duty to balance the task of keeping the streets open with the right freedom of assembly under the Article 11 of the Human Rights Act 1998 and freedom of expression, under Article 10. These rights are not absolute – the state can curtail them.
However, the BBC’s home affairs correspondent Dominic Casciani said: “The test, if and when it gets to a court battle, is whether police action was proportionate to threat and only what was strictly necessary.”
By law, the organiser of a public march must tell the police certain information in writing six days in advance.
Police have the power to limit or change the route of the march or set other conditions.
A Section 14 notice issued under the Public Order Act allows police to impose conditions on a static protest and individuals who fail to comply with these can be arrested.
Extinction Rebellion activists have glued themselves to one government department and to the underside of a lorry outside another on a second day of protests in central London.
Police have made more than 400 arrests, and those camped out in Westminster have been ordered to move on.
The prime minister has described the activists as “unco-operative crusties”.
But campaigner and TV presenter Chris Packham said they are “the concerned people of the world.”
Extinction Rebellion activists are protesting in cities around the world, including Berlin, Amsterdam and Sydney, and are calling for urgent action on global climate and wildlife emergencies.
Protesters say they are occupying 11 sites in central London and people have travelled from across the UK to take part in the demonstrations.
The Metropolitan Police said at 13:00 BST on Tuesday there have been 404 arrests in relation to them.
Activists have attached themselves to the underside of a lorry, which is blocking the road outside the Home Office.
The vehicle is parked on Marsham Street, where hundreds of protesters set up camp overnight. One activist climbed on top of the lorry and set up a tent.
There was a large police presence in the area on Tuesday, with pictures showing officers removing activists from the lorry.
Protesters have also glued themselves to the Department for Transport building – a tactic used in similar protests in April.
Two activists have attached themselves to the doors of the building, while others demonstrate outside.
Meanwhile, a group have placed 800 potted trees outside Parliament, in Old Palace Yard, as they call on the government to plant billions of trees across the UK.
Trees have been dedicated to MPs, and protesters hope they will use them to reforest the country.
Sean Clay, 36, from Newcastle, told the BBC: “Planting trees would go a long way to restore the habitats we have lost as well as absorbing carbon emissions.”
Asked about Boris Johnson’s description of demonstrators, Packham told the BBC’s Victoria Derbyshire programme: “I was there yesterday. I met farmers, I met teachers, I met scientists, I met lawyers, I met grandparents, I met mothers and fathers, and I met children.
“These are the concerned people of the world.”
Mr Johnson had suggested while attending a book launch on Monday that the demonstrators should abandon their “hemp-smelling bivouacs” and stop blocking roads.
Protester Claudia Fisher, 57, from Brighton said campaigners would like to discuss their views with the prime minister.
Responding to his description of activists as “unco-operative crusties”, Ms Fisher said: “We are a little bit crusty, I’ll put my hands up to it, after a night sleeping out on the grounds of Whitehall, but we’re not uncooperative.
“We’re actually very cooperative. We… would really like to hear what he has to say, and we’d really like him to… hear what we have to say.”
John Curran, a 49-year-old former detective sergeant for the Metropolitan Police, was one of the protesters who camped overnight.
Mr Curran, who has a three-year-old daughter, says he was arrested while protesting with Extinction Rebellion in April, and is willing to be arrested again.
He said: “Clearly there is some frustration (for the police) that they probably have better things to be doing, and I agree, but the responsibility for that must lie with the government.
“Take action, and we won’t have to be here.”
Protesters who camped in Horseferry Road and Marsham Street, in Westminster, throughout the night were warned that they will be arrested unless they move to nearby Trafalgar Square. Police handed out section 14 notices to tents at around 07:30 BST.
Activists also camped at Smithfield Market overnight, but they say they allowed traders to operate.
‘A last resort’
By Becky Morton, BBC News
The only rush hour traffic around Parliament this morning came from cyclists, who were cheered as they passed encampments of protesters dotted around Westminster.
Roads have been blocked by tents and gazebos, with protesters from all over the country camping overnight.
Bowls of porridge were served from food trucks, while volunteers said some local businesses had donated pastries.
One of those who spent the night here is Mikaela Loach, 21, who travelled down by bus from Edinburgh with a friend.
She said taking part in this week’s action was a “last resort”.
“I’ve spoken to my local MP, I’ve taken part in protests, I just feel like I haven’t been listened to,” she said.
“I have been changing things in my lifestyle for a long time to try and be more eco-friendly, but I had a realisation a few months ago that it doesn’t matter if I go vegan or zero waste if the government doesn’t do anything.
“There need to be big structural changes.”
Further road closures are expected on Tuesday, with Parliament Street, Great Smith Street and Westminster and Lambeth bridges predicted to be heavily affected.
Extinction Rebellion claims protests in the capital will be five times bigger than similar events in April, which saw more than 1,100 people were arrested.
What is Extinction Rebellion?
2025year when the group aims for zero carbon emissions
298,000followers on Facebook
1,130people arrested over April’s London protests
2018year the group was founded
Source: BBC Research
Extinction Rebellion (XR for short) wants governments to declare a “climate and ecological emergency” and take immediate action to address climate change.
It describes itself as an international “non-violent civil disobedience activist movement”.
Extinction Rebellion was launched in 2018 and organisers say it now has groups willing to take action in dozens of countries.
In April, the group held a large demonstration in London that brought major routes in the city to a standstill.
An Extinction Rebellion co-founder has appeared in court charged with attempting to cause disruption at Heathrow airport using a drone.
Roger Hallam, 53, who declared Heathrow expansion “a crime against humanity”, was arrested on Saturday.
He was applauded by a group of supporters as he entered the dock at Uxbridge Magistrates’ Court on Monday.
Mr Hallam faces one charge of conspiring to cause a public nuisance between 1 August and 14 September.
The charge relates to a plan to fly drones near Heathrow airport “in order to cause widespread disruption”.
The action was part of ongoing protest activity by environmental campaign group Extinction Rebellion (XR).
A splinter group of XR, called Heathrow Pause, had threatened to interrupt flights by flying drones within the 5km exclusion zone around the airport.
Asked if he would like to say anything, Mr Hallam, of Putney Bridge Road, Wandsworth, told the court: “Heathrow expansion constitutes a crime against humanity, against the next generation.”
He was remanded in custody to appear at Isleworth Crown Court on 14 October.