This comes as demonstrators from Insulate Britain, a climate group started by one of Extinction Rebellion’s founders, stopped traffic on the motorway on Wednesday - the seventh time they have done so in little more than fortnight.
Protesters have also recently blocked other key roads such as the A20 near the Port of Dover.
Last week, the government warned climate campaigners they could be charged with contempt of court if they ignored an interim injunction issued by the High Court on 22 September. Under this restriction, protesters are banned from occupying strategic roads.
A spokesperson for the government confirmed on Wednesday that it had begun to serve papers to people accused of breaching it.
“Police continue making arrests and are working closely with National Highways to shut down these illegal demonstrations and keep the public safe,” they added.
Those who take part in such protests face unlimited fines or up to two years in prison.
A total of 11 arrests were made on Wednesday morning at junction 3 in Kent, after activists glued themselves to the road on a roundabout.
A further 16 people were also detained for obstructing the highway at the same spot in the afternoon.
Insulate Britain said in a statement: “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.”
The demonstrators on the M25 welcomed a promise from Keir Starmer that his party would insulate every home in Britain over the next 10 years. The Labour leader mentioned the pledge during a speech at the party’s conference on Wednesday.
“That’s excellent news. Let’s get the Labour Party in,” one woman said.
Additional reporting by PA
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