Extinction Rebellion: Climate protesters 'making a difference'
A teenage climate change activist has told Extinction Rebellion protesters in London they are "making a difference".
Greta Thunberg, 16, was greeted with chants of "we love you" as she took to the stage in front of thousands of people at the rally in Marble Arch.
A protest organiser said they planned "a week of activities" including a bid to prevent MPs entering Parliament.
More than 950 people have been arrested during the climate change protests and 40 people have been charged.
Ms Thunberg, a Swedish teenager who is credited with inspiring an international movement to fight climate change, told the crowd "humanity is standing at a crossroads" and that protesters "will never stop fighting for this planet".
Addressing the crowd at about 19:30 BST, she said: "For way too long the politicians and people in power have got away with not doing anything at all to fight the climate crisis and ecological crisis.
"But we will make sure they will not get away with it any longer."
As of 19:00 on Sunday, a total of 963 people had been arrested during the climate change protests.
The Met Police said 40 people, aged 19 to 77, have been charged for "various offences including breach of Section 14 Notice of the Public Order Act 1986, obstructing a highway and obstructing police".
Extinction Rebellion said it hoped to negotiate with the Mayor of London and the Met over continuing its demonstrations at Old Palace Yard in Westminster and leaving other sites.
Organisers said there would be a "people's assembly" at Marble Arch on Monday afternoon to decide what will happen in the coming week.
At the scene
By Dan Coles, BBC News
For much of the day there had been several hundred people at Extinction Rebellion's Marble Arch site.
But the chance to hear from Greta Thunberg - something of a celebrity in the climate protest world - saw the numbers swell into the thousands. The crowd was bolstered by an influx from the Parliament Square location and their banners filled the air.
Greta Thunberg's two-day journey to London by train was eagerly followed on social media and she got a huge cheer as she finally took to the stage.
Her speech was short and sweet, but the message was exactly what the crowd wanted to hear: "Keep going. You are making a difference."
Earlier, Extinction Rebellion member Farhana Yamin said the group had offered to "pause" protests and begin "a new phase of rebellion" to achieve "political aims".
She said the move would show the group was an "organised and a long-term political force to be reckoned with".
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However, another Extinction Rebellion organiser Larch Maxey told the BBC there "certainly won't be a pause in our activities".
He said: "On Tuesday we've got a series of strategic points around the city which we will be targeting to cause maximum economic disruption while simultaneously focusing on Parliament and inviting MPs to pause."
Asked if MPs would be able to get into Parliament, he added: "Not if we are successful, we're going to prevent them getting in so they have time to separate themselves from the politicking and concentrate on what's at stake here."
Police have been trying to confine the protests to Marble Arch but demonstrators have ignored the threat of arrest and continued to block roads across the capital.
Areas around Oxford Circus and Parliament Square have reopened to traffic after officers cleared protesters.
On Sunday afternoon, police removed the skate ramp, cooking tents and other infrastructure from the activists' camp on Waterloo Bridge.
Some protesters began removing their collection of trees and plants, and officers removed the last activist from the bridge at about 22:00.
Met Commissioner Cressida Dick said that during her 36-year career she had never known a single police operation to result in so many arrests.
She said she was grateful for the help from hundreds of police officers drafted in from several forces , including the neighbouring City of London Police.
Officers from Kent, Sussex, Essex, Hampshire and Greater Manchester have also been sent.
Mayor of London Sadiq Khan said "more than 9,000 officers" had been responding to the demonstrations and he was "extremely concerned" about their impact on tackling issues such as violent crime.
What is Extinction Rebellion?
Since the group was set up last year, members have shut bridges, poured buckets of fake blood outside Downing Street, blockaded the BBC and stripped semi-naked in Parliament.
It has three core demands : for the government to "tell the truth about climate change"; to reduce carbon emissions to zero by 2025; and to create a citizens' assembly to oversee progress.
Controversially, the group is trying to get as many people arrested as possible.
But critics say they cause unnecessary disruption and waste police time when forces are already overstretched.