Just Stop Oil supporters are protesting on the M25 for the fourth consecutive day.
Surrey Police said officers are dealing with activists who climbed a gantry at Junction 8 of the UK’s busiest motorway.
The road has been closed in both directions while officers climb the gantry.
The force said: “One lane was closed for a short time as officers responded to the situation.”
The Metropolitan Police said: “We’re ready to respond to any criminality on the M25 again today and will work quickly to minimise disruption and keep traffic moving.”
Kent Police said: “There are no current incidents involving activists on the road networks in Kent.
“Our officers are continuing to assist other forces in responding to any offences and disruption elsewhere.”
The Met said there is a person on a gantry near Junction 25 at Waltham Cross close to the border with Hertfordshire.
The road is closed.
There was also a report on social media of a protest between Junctions 15 and 16, near Heathrow Airport.
Just Stop Oil said its supporters climbed gantries “in multiple locations” from 6.30am on Thursday.
Phoebie Plummer, a 21-year-old student from London, said: “I understand people must be frustrated with us, and rightly so, but we have to disrupt daily life because we are hurtling towards climate catastrophe, yet the Government continues to betray me, my generation and people in the global South by issuing new oil licences.”
A police officer was injured during Wednesday’s protests.
Essex Police said there was a collision involving the police motorcyclist and two lorries during a rolling roadblock.
Chief Constable BJ Harrington warned it is “only a matter of time” before someone is killed during a Just Stop Oil protest.
Meanwhile, three people have been charged following Just Stop Oil protests at multiple junctions on the M25 on Wednesday, Essex Police said.
Daniel Johnson, 24, of Blairgowrie, Perth and Kinross, Paul Bell, 20, of St Germans Road, Exeter and Theresa Higginson, 24, of Biggleswade, Bedfordshire, have all been charged with causing a public nuisance and have been remanded in custody.
They will appear at Basildon Magistrates’ Court via video link later on Thursday.