The motorway was reopened within half an hour, Essex Police says.
Image source, Insulate Britain
Insulate Britain protesters caused delays on the M25 by walking alongside oncoming traffic, police said.
The protest group said the decision to stop sitting in the middle of roads had been made following “feedback” from frustrated drivers.
Essex Police said it was called to a stretch of the motorway between junctions 28 and 29 near Great Warley at 08:00 BST and 10 arrests were made.
It said both sides of the carriageway were reopened within half an hour.
Protesters later began walking along the white lines of the motorway near junction 21a for Bricket Wood at about 10:30 BST.
Hertfordshire Police said on Twitter that officers were “working to resolve the disruption as quickly as possible” and “several arrests” had been made.
Image source, Essex Police
Ch Insp Lee Deval, of Essex Police, said: “Not only will incidents of this nature be frustrating for road users trying to reach their destination, walking into fast-moving traffic is extremely dangerous.
“I’d like to thank road users today for their patience and understanding.
“You’ve helped us to clear the area quickly, to keep people safe, minimise disruption, and keep Essex moving.”
Four court injunctions are in place banning Insulate Britain from obstructing major roads.
In a post on Twitter, the group said “14 ordinary people” had caused major disruption on the motorway and were defying the government injunction.
Image source, Essex Police
This is the group’s 17th day of action, the last of which saw members have ink thrown in their faces.
Speaking before Friday’s protest, a man calling himself “Biff” said: “We’ve had feedback that people are frustrated that they spent time in traffic queues.
“We’re not planning to stop traffic but it could slow down to five miles an hour.”
The campaigning organisation has been calling for a national programme to ensure homes are insulated to be low energy by 2030.
It has blocked major roads around London in recent weeks, including the M1, M4 and M25.
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