In a major blow to the government, three judges today found that the “nature and scale” of the group’s activities had “not yet reached the level, scale and persistence that would justify” proscription.

They said this was the case even though they agreed that Palestine Action “has organised and undertaken actions” which amount to terrorism as defined in section 1(1) of the Terrorism Act 2000.

Finding that the ban was “disproportionate”, the judges said: “At its core, Palestine Action is an organisation that promotes its political cause through criminality and encouragement of criminality. A very small number of its actions have amounted to terrorist action within the definition at section 1(1) of the 2000 Act.”

The court will now consider whether to make an order quashing the decision to proscribe Palestine Action or to stay this pending further appeals.

In a statement, the UK’s home secretary, Shabana Mahmood, said: “I am disappointed by the court’s decision and disagree with the notion that banning this terrorist organisation is disproportionate.

“The proscription of Palestine Action followed a rigorous and evidence-based decision-making process, endorsed by Parliament.

“The proscription does not prevent peaceful protest in support of the Palestinian cause, another point on which the court agrees.

“As a former lord chancellor, I have the deepest respect for our judiciary. Home secretaries must however retain the ability to take action to protect our national security and keep the public safe.

“I intend to fight this judgment in the Court of Appeal.”

Palestine Action co-founder Huda Ammori brought the High Court action, in which a UN special rapporteur, Amnesty International UK and Liberty intervened.

“This is a monumental victory both for our fundamental freedoms here in Britain and in the struggle for freedom for the Palestinian people, striking down a decision that will forever be remembered as one of the most extreme attacks on free speech in recent British history,” she said.

“Palestine Action is the first civil disobedience organisation that does not advocate for violence to be proscribed by the British government as a ‘terrorist’ group, in a Trumpian abuse of power which would have seen this Labour government proscribe the suffragettes.

“This ban was unlawful, resulting in the unlawful arrest of nearly 3,000 people – among them priests, vicars, former magistrates and retired doctors – under terrorism laws for simply sitting in silence while holding signs reading: ‘I oppose genocide, I support Palestine Action’.”

A separate challenge is still underway at the Court of Session.