Tougher punishments are set to be introduced by the government to deal with climate change activists, who have blocked motorways and caused disruption in recent weeks.
During the Tory Party conference in Manchester, Home Secretary Priti Patel is expected to warn protestors who block the motorway could face unlimited fines and up to six months in jail.
Police will also be given powers to stop and search activists for "lock-on" equipment used to prevent them from being moved.
The move follows days of protests by Insulate Britain, which has staged sit-down demonstrations on a series of key roads around London - including on the M25, M1 and M4.
On 2 October, the government obtained a fresh injunction banning the group from obstructing traffic and access to motorways and major A roads around London.
The new powers will be introduced by Ms Patel and added as an amendment in the Police, Crime, Courts and Sentencing Bill, currently going through parliament.
Ministers believe that, while they accept the right to protest, the current techniques used by Insulate Britain and its associated punishment - a maximum fine of £1,000 - does not reflect the seriousness of the disruption caused.
Ahead of her conference speech, Ms Patel said: "The right to protest is a fundamental principle of our democracy but we will not tolerate guerrilla tactics that obstruct people going about their day-to-day business.
"Whilst the Labour Party stand on the side of these so-called 'activists', the Conservative party will always back the law-abiding, hard-working majority of people in this country."
Prime Minister Boris Johnson added: "This government will always stand on the side of the law-abiding majority and ensure the toughest penalties possible for criminals who deliberately bring major roads to a standstill.
"We will give the police the powers they need to stop their reckless and selfish behaviour."