“Overall the court considered that the proscription of Palestine Action was disproportionate. A very small number of Palestine Action’s activities amounted to acts of terrorism,” the judges ruled.

The proscription resulted in a “very significant interference with the right to freedom of speech and free assembly”, the judges ruled.

The government reacted swiftly, with interior minister Shabana Mahmood saying she would appeal.

“I am disappointed by the court’s decision and disagree with the notion that banning this terrorist organisation is disproportionate,” she said.

“Home secretaries must …  retain the ability to take action to protect our national security and keep the public safe. I intend to fight this judgement in the Court of Appeal.”

Cheers erupted outside the court when the judgement was read out on Friday.

But judges ruled the ban brought in July under the UK’s 2000 Terrorism Act would remain in place pending an appeal.

Nearly 3,000 people, some aged in their 80s, have been arrested and hundreds charged for showing support for Palestine Action at demonstrations since July.

Most were detained for holding up posters in support of the group, according to protest organisers Defend Our Juries.