Insulate Britain activists said they have “failed” but are now planning an “even more ambitious” campaign.

The group, which orchestrated a number of protest roadblocks on the M25 and other key roads in 2021, said on Monday they are “just getting started” as they promised to continue demonstrating despite some members being jailed.

A number of activists were handed prison sentences after breaching an injunction aimed at curbing their climate change protests.

The environmental campaign group said in a statement: “It is with an extremely heavy heart that today we have to announce that as Insulate Britain we have failed.

“We failed to move our irresponsible Government to take meaningful action to prevent thousands of us from dying in our cold homes during the energy price crisis.

“We have failed to make this heartless Government put its people over profit and insulate our homes to do our part in lowering the UK’s emissions.

“We have failed to encourage our Government to get up from their drinks parties, go to their desk and get on with the job.

“And we failed in getting enough of you to join us on the roads to hold this treasonous and corrupt Government to account.”

Insulate Britain blocked roads several times between September 13 and November 20 2021.

The group said its mission was to urge the Government to insulate all of Britain’s homes by 2030 to cut carbon emissions.

They added: “We will continue our campaign of civil resistance because we only have the next two to three years to sort it out and prevent us completely failing our children and hitting climate tipping points we cannot control.

“Now we must accept that we have lost another year, so our next campaign of civil resistance against the betrayal of this country must be even more ambitious.

“More of us must take a stand. More of you need to join us. We don’t get to be bystanders. We either act against evil or we participate in it.

“We haven’t gone away. We’re just getting started.”

National Highways, the organisation that manages England’s major roads, brought contempt of court proceedings against protesters, accusing them of breaking an injunction granted in September aimed at curbing the blockades.

A spokesperson for the National Police Chiefs’ Council, the national co-ordination body for law enforcement in the UK, said: “Police will continue to respond in a timely way, taking any appropriate and proportionate action in the event of further protest activity of this kind.

“We would urge those protesting to highlight their cause in a reasonable manner, and in a way that shows respect and regards for the rights of others.”

They added: “Where lawful, we will seek to facilitate peaceful protests, but even if the protest is peaceful, this doesn’t always mean the actions taken by those protesters are legal.

“Each event or protest will be assessed on its particular circumstances, but policing decision making must be consistent and fair, and ultimately accountable to the law. That assessment does not include the cause or issue for the protest – all groups or causes are treated impartially.”