A new injunction granted by the High Court and lasting almost a year could see Just Stop Oil activists face fresh penalties for demonstrating on the M25.

National Highways said it secured the civil order to “prevent unlawful protests” on the country’s busiest motorway after a series of stunts during which members of the environmental group scaled gantries and caused major traffic disruption.

The injunction, granted on Monday before Mr Justice Soole, will remain in place until just before midnight on November 15 2023 or until further order.

It means that anyone entering, remaining upon or affixing themselves to any object or to any structure on the M25 may have civil proceedings launched against them for contempt of court.

They could face imprisonment, an unlimited fine, the seizure of assets or a combination of these sanctions.

Some 65 individuals who were arrested by police as a result of their involvement in Just Stop Oil protests on the M25 gantries are named specifically in the injunction.

This includes some individuals supporting protests from Animal Rebellion and Insulate Britain, according to National Highways.

The injunction was secured in addition to a court order obtained by National Highways earlier this year that targeted protesters including those from Insulate Britain.

Transport Secretary Mark Harper said: “The reckless, selfish actions of a small group of protestors has stopped children getting to school, people getting to work, and emergency service workers from their critical work.”

He added: “Free speech and lawful protest is a cornerstone of our democracy, but putting peoples safety and livelihoods at risk due to selfish and unlawful protest activity will not be tolerated.”

Sean Martell, National Highways’ head of service delivery in the South East, said: “Millions of people rely on the strategic road network every day and they have a right to expect it to operate as it should.

“Climbing on structures such as gantries is extremely dangerous – both for the protesters themselves and motorists – and we’re committed to doing all we can to seek to prevent a small minority from causing disruption on the network.

“We’re extremely concerned that the M25 will continue to be targeted by protesters and this underlines the importance and need for the civil injunctions to deter unlawful protest activity.”

It comes after a group of five Just Stop Oil activists received suspended prison sentences for breaching an injunction by blocking access to a petrol station.

Ruth Cook, 70, Joy Corrigan, 71, Dr Patrick Hart, 36, Stephen Jarvis, 66, and George Oakenfold, 78, all admitted breaking terms of a civil order granted to Thurrock Council and Essex County Council.

The local authorities secured the injunction in May to “restrain unlawful acts of protest” in their areas, including forbidding blocking any petrol station and interfering with deliveries or refuelling, the court was told.

Mr Justice Bourne said the case involved a “deliberate flouting of a court order” and that the harm caused was “not lessened” by protesters having “conscientious motives”.