Parts of the M25 have been temporarily closed after Just Stop Oil protesters climbed overhead gantries and caused disruption on the major motorway circling London.
It comes despite the Metropolitan Police “proactively” arresting campaigners last night suspected of planning action on UK motorways.
Surrey Police said a decision was made to close sections of the M25 during the morning rush hour on Monday “for the safety of everyone” while officers removed activists.
The force said it had received reports of protesters scaling gantries at several junctions along the M25 – including between junctions 6 and 7, junctions 8 and 9, and junctions 9 and 10.
“We are here and dealing and will get this resolved as soon as possible,” it tweeted, adding activists had been removed and arrested for public nuisance from those sections of the motorway, with traffic resuming.
A protester also targeted junction 30 of the motorway, with Essex Police urging the public “not to intervene”.
“We are continuing to work to resolve the situation on the #M25 as quickly and safely as possible. Officers responded quickly this morning and have already made arrests,” the force tweeted.
Just Stop Oil activists spray orange paint over Home Office, MI5, News UK and Bank of England buildings
Just Stop Oil activists spray orange paint on Rolex store in Knightsbridge
Just Stop Oil protesters spray paint over Bentley, Ferrari and Bugatti showrooms in London
Meanwhile, Hertfordshire Police said it was dealing with similar action on the M25 at junctions 22 and 23.
“The junction 22 #M25 road closure has now been lifted. All protestors have been removed and some 5 people have been arrested,” it tweeted.
The Met had earlier said its “significant” operation had resulted in at least three people being detained, who the force had “strong reason to believe are intent on causing reckless and serious disruption to the public”.
In a statement released late on Sunday, Assistant Commissioner Matt Twist said: “Acting on intelligence, this operation is fast-moving and will continue this evening and overnight with multiple arrest inquiries under way.
“So far this evening we have made three arrests linked to this activity.
“Our investigation has strong reason to suspect the Just Stop Oil group intend to disrupt major motorway road networks which would risk serious harm to the public, with reckless action to obstruct the public on a large scale.”
The suspects were arrested for allegedly conspiring to cause public nuisance, according to the Met Police.
Mr Twist warned there “remains a possibility” that other suspects are “still intent on causing unlawful disruption to the public”.
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National Highways has secured a High Court injunction to prevent Just Stop Oil protesters disrupting England’s busiest motorway.
The court has granted a further injunction which aims to stop unlawful demonstrations on the M25, which encircles Greater London, in an attempt to end disruption to the busy road by the environmental group.
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It means that anyone entering the motorway and fixing themselves to any object or structure on it, and anyone assisting in such an act, can be held in contempt of court.
They could face imprisonment, an unlimited fine, and the seizure of assets.
Just Stop Oil has attracted widespread attention, and fierce criticism, in recent weeks for their stunts which have involved spraying orange paint on buildings and scaling a bridge to force the closure of the M25 Dartford Crossing.
The climate change activists staged 32 days of disruption from the end of September and throughout October, which the Met said resulted in 677 arrests with 111 people charged.
The protesters have been calling on the government to abandon plans to licence more than 100 new oil and gas projects by 2025, and to do more to help people with their skyrocketing energy bills.