Dozens of climate change activists have been arrested over action to target England's busiest motorway despite a police operation to foil their plans.
Sections of the M25 were closed during the Monday morning rush hour as part of the protest by Just Stop Oil.
The demonstrations come as the latest COP27 international climate change talks in Egypt get under way.
The Met Police said 35 people had been arrested in response to the disruption.
Assistant Commissioner Matt Twist said the action was "criminality", not protest, and pledged to bring those involved to justice as quickly as possible.
"This was a very significant and co-ordinated effort to cause massive disruption to the entirety of the M25," he added.
Several junctions across Surrey, London and Kent were affected.
Protests were held at several locations on the M25 including: J2 (Darenth), J6-7 (Godstone), J8-9 (Reigate), J13-14 (Staines), J21a-22 (St Albans), J25 (Holmesdale tunnel) and J27 (M11).
In an emotional video posted from one of the gantries, protester Louise said she was there because she felt she did not "have a future and you may hate me for doing this, and you're entitled to hate me, but I wish you would direct all that anger and hatred at our government".
The 24-year-old added: "They are betraying young people like me. I wouldn't have to be there if they did their lawful duty.
"What we're asking for is what all the scientists are asking for, what the United Nations are asking for... how many more people have to say 'we don't have a liveable future if you continue licensing oil and gas' for you to listen?"
The Met Police said it had launched a "significant" operation to identify and arrest the climate change protesters.
Three people accused of planning public disruption were "proactively" arrested on Sunday, according to the Met.
They were detained on suspicion of "conspiracy to intentionally or recklessly cause public nuisance", a new offence under the Police, Crime, Sentencing and Courts Act 2022.
A further four were arrested in raids on Monday morning.
'Genocidal death project'
Mr Twist said: "We suspected that the intent of the individuals involved was completely disproportionate to any legitimate right to protest."
Supt Graham Barnett from Surrey Police said: "While we always seek to facilitate peaceful protests, the protests we've seen today have gone beyond that.
"Whilst they've been peaceful, the impact that they've had has not been proportionate on the public."
On Sunday, a High Court injunction was granted to prevent Just Stop Oil protesters disrupting the M25.
From the end of September and throughout October, Just Stop Oil staged 32 days of protests, which the Met said resulted in 677 arrests, leading to 111 people charged.
According to the group, since its campaign began on 1 April, its supporters have been arrested nearly 2,000 times, with five of its supporters currently in prison.
The Met, which is conducting the operation in conjunction with the National Police Coordination Centre (NPoCC), said more than 10,000 officer shifts had been dedicated to policing the protests since the start of October.
"These are officers who would otherwise be dealing with issues that matter to local communities, such as knife crime, safeguarding and responding to burglaries," Mr Twist said.
"We are determined to bring to justice all of those who conspire to cause significant and unreasonable disruption to London, or cause damage to buildings, property or valuables," he added.
Police are calling on the public to help officers help prevent disruption caused by protesters.
Just Stop Oil wants the government to abandon plans to license over 100 new oil and gas projects by 2025 and to do more to help people with rising energy bills.
In an update on its website, the group said: "This is not a one-day event, expect us every day and anywhere.
"This is an act of resistance against a criminal government and their genocidal death project.
"Our supporters will be returning - today, tomorrow and the next day - and the next day after that - and every day until our demand is met: no new oil and gas in the UK."
Just Stop Oil said on social media that on Sunday evening it had "contacted the Metropolitan Police and National Highways Ltd to advise them there would (be) major disruption on the M25 and asked them to implement a 30mph speed limit".
A government spokesperson said: "While we respect the right to protest, people's day-to-day lives should not be disrupted, and criminal activity will not be tolerated."