The group said 50 activists had blocked four commuter routes– Blackwall Tunnel, Wandsworth Bridge, Hanger Lane and Arnos Grove – as they turned their attention to the capital.
Police said they had made 38 arrests for disruption of the highway and conspiracy to cause public nuisance.
Builders and angry motorists dragged protesters out of the road before police could arrive in Wandsworth Bridge at 9am.
One driver urged other motorists to “just drive over them” in clashes with a dozen activists sat in the road. An ambulance driver was also seen pleading with the group, in high-vis jackets, to be let through.
At the Blackwall Tunnel a protester was hit by the driver of a grey van as he attempted to swerve the roadblock. The activist, who was unharmed, managed to hold the protest line and keep a grip on his Insulate Britain banner.
Two police officers were pictured standing behind the group of protesters as they sat at the entrance to the Blackwall Tunnel.
One woman was filmed by LBC begging to be let through the roadblock to see her mother who was being rushed to hospital in Canterbury.
'How can you be so selfish?!'
This desperate motorist pleads with eco protesters blocking the entrance to the Blackwall Tunnel asking them to move so she can get to her sick mother in hospital.
Read More: https://t.co/2zubNjd9kj pic.twitter.com/gTaPeAWg1Y
— LBC (@LBC) October 4, 2021
She shouted: “I used to support you but not now. How can you be so selfish? I don't think you understand she’s 81 and in hospital. Bloody move then... I want this to be on your conscience.”
BREAKING: Insulate Britain activists have blocked Wandsworth Bridge in South London in protest against government “inaction” on climate change. More follows… pic.twitter.com/DyPHEEVhDi
— talkRADIO (@talkRADIO) October 4, 2021
Insulate Britain spokesperson Tracey, a full-time mother from Milton Keynes said: “We’re more scared of what will happen when the climate crisis causes the breakdown of law and order, than we are of injunctions and prison.
“The government is focussing on us rather than what’s coming down the road. They need to face up to reality.”
A Metropolitan Police spokesman said: “We consider protests of this nature unreasonable and are acting as quickly as possible to minimise disruption caused to members of the public using the roads.”
It came as the Government is to introduce tougher powers to deal with climate change activists, who have caused chaos on the roads by blocking motorways.
At the Tory Party conference in Manchester, Home Secretary Priti Patel will warn that protesters who block the highway could face unlimited fines and up to six months in jail.
Police are also to be given the powers to stop and search activists for “lock-on” equipment used to prevent them from being moved.
The move follows days of protests by the Insulate Britain group, which has staged sit-down demonstrations on a series of key arteries around London, including on the M25, M1 and M4.