The Government has said legal proceedings have begun against green activists who face fines or prison for blocking the M25.
Protesters from Insulate Britain, an offshoot of Extinction Rebellion, have been warned by the Government they will be served injunction papers by High Court enforcement officers over their series of protests in recent weeks.
Watch: Angry drivers attempt to move Insulate Britain protesters from M25
Activists were told if there is evidence that they have breached the injunction they will be subject to proceedings in the High Court, where they could face unlimited fines or jail.
A Government spokesperson said: “Peaceful protest is a fundamental right of our democracy, but we cannot allow this reckless and dangerous behaviour to continue on our roads.
“We are already knocking on doors and serving papers to offenders who will be sent to court and could face fines or prison.
“Police continue making arrests and are working closely with National Highways to shut down these illegal demonstrations and keep the public safe.”
The action comes after Insulate Britain targeted the same junction of the motorway twice in six hours on Wednesday.
Activists glued themselves to the road on a roundabout at junction 3, the Swanley Interchange in Kent, at around 7.30am on Wednesday.
Eleven people were arrested on suspicion of obstructing the highway and conspiracy to commit criminal damage as the demonstration was cleared.
But the group returned at 1pm when a further 16 arrests were made for the same offence.
All 27 people are being held in custody.
The High Court injunction obtained by the Government on September 22 means anyone blocking the motorway could be found to be in contempt of court, which carries a maximum penalty of two years in prison or an unlimited fine.
Police have said it is “very difficult” to bring charges against the activists, who staged their seventh day of action on the M25 on Wednesday.
Lisa Townsend, Surrey’s Police and Crime Commissioner, said officers are receiving “an enormous amount of flak” over their response.
She said: “It has been very difficult for the police because if they charge the protesters with a relatively minor offence, it is likely to be discontinued.
“If they try to elevate the charge to a more serious one, they are finding it is not reaching the necessary threshold.
“The public deserves to see a response from all parts of the criminal justice system and it is unfair for the police to be blamed if people do not end up before the courts.”
A statement from Insulate Britain said: “We are going nowhere. You can raid our savings. You can confiscate our property. You can deny us our liberty and put us behind bars.
“But shooting the messenger can never destroy the message: that this country is going to hell unless you take emergency action to stop putting carbon into the air. Boris get on with the job.”
Activists welcomed a pledge by Labour leader Sir Keir Starmer to insulate every home that needs it in Britain over the next decade.
One woman glued to the road said: “That’s excellent news. Let’s get the Labour Party in.
“It would cut UK emissions by 15%, it’s the easiest thing to do.”
Another woman added: “When will the Conservatives do the same thing?”
As well as targeting the London ring road, protesters have blocked other important routes including the A1(M) and A20 near the Port of Dover.