Greta Thunberg arrested in London protest under UK terrorism legislation

Swedish climate activist Greta Thunberg was arrested in London during a pro-Palestinian protest and later released on bail, British police said, after authorities determined she had displayed a sign supporting a group proscribed under UK terrorism laws. The arrest comes amid heightened scrutiny of protests linked to the Israel–Gaza conflict and follows earlier legal cases involving Thunberg in Britain.

Greta Thunberg, one of the world’s most recognisable climate activists, was arrested on Tuesday during a protest in London and later released from custody, according to City of London Police.

Police said Thunberg, 22, was detained after attending a demonstration where a placard was displayed in support of a proscribed organisation. She was subsequently bailed to return at a later date, with conditions extending until March, authorities said.

The arrest occurred during a protest connected to Palestine Action, a UK-based campaign group that the British government has formally designated as a terrorist organisation. Under UK law, it is a criminal offence to express support for groups that have been proscribed under the Terrorism Act.

Arrest linked to support for banned organisation

A UK-based campaign group, Prisoners for Palestine, said Thunberg was arrested under the Terrorism Act after holding a sign that read: “I support the Palestine Action prisoners. I oppose genocide.”

Police confirmed that a 22-year-old woman was arrested at the scene on suspicion of displaying material in support of a proscribed organisation. While officers did not initially name Thunberg, Prisoners for Palestine publicly identified her as the individual detained.

City of London Police said two other individuals were arrested earlier in connection with the same protest for allegedly throwing red paint at a nearby building. The force said officers later arrested an additional person who arrived at the scene and displayed a placard referring to the banned group.

No further charges were announced on Tuesday, and police said investigations were ongoing.

Protest target and claims by campaigners

Prisoners for Palestine said the protest targeted a building used by an insurance firm that it claims provides services to the British subsidiary of Israeli defence company Elbit Systems. Elbit Systems is a major Israeli defence manufacturer that has previously been the focus of protests by pro-Palestinian activists in the UK.

The insurance company did not immediately respond to requests for comment. British authorities have not publicly confirmed any link between the firm and Elbit Systems in connection with the incident.

Palestine Action has staged repeated protests in recent years against companies it says are connected to Israeli military operations. The UK government proscribed the group earlier this year, citing concerns about serious criminal damage and national security.

Legal framework and protest policing

Under the UK Terrorism Act, it is an offence to invite support for, or publicly express support for, a proscribed organisation. Convictions can carry significant prison sentences, although police and prosecutors must assess whether actions meet the legal threshold for charges.

British police forces have faced increasing pressure to balance the right to protest with enforcement of terrorism and public order legislation, particularly as demonstrations linked to the Israel–Gaza war have intensified across the country.

Civil liberties groups have warned that broad application of terrorism laws could have a chilling effect on lawful protest. Government ministers, however, have defended the legislation, saying it is necessary to prevent support for groups involved in serious criminal activity.

Thunberg’s history of activism and legal cases

Thunberg rose to international prominence in 2018 after beginning weekly school strikes outside the Swedish parliament to demand stronger action on climate change. Her activism quickly gained global attention, inspiring similar protests worldwide and leading to appearances at major international forums.

In recent years, she has broadened her activism to include issues related to social justice and international conflicts, including the war in Gaza. Her public support for Palestinian civilians has drawn both praise and criticism, particularly from political leaders who argue that such statements oversimplify a complex conflict.

Thunberg has previously faced legal action in the UK. Last year, she was cleared of a public order offence after a British judge ruled that police had acted unlawfully in arresting her and other protesters during a demonstration in London the previous year.

The ruling centred on whether police had properly imposed conditions on the protest under public order laws. The judge found that officers lacked the legal authority to make the arrests at that time.

Previous detention linked to Gaza aid flotilla

In October, Thunberg was detained by Israeli authorities after joining an activist convoy known as the Global Sumud Flotilla, which attempted to reach Gaza carrying aid supplies. Israeli officials said the vessels were prevented from entering restricted waters.

Thunberg was among hundreds of activists detained and later expelled from Israel following the incident. Israeli authorities said the flotilla violated security restrictions imposed around Gaza.

Israel has repeatedly rejected allegations of genocide in Gaza, describing its military operations as acts of self-defence following attacks by Hamas. The issue has been the subject of international legal and diplomatic debate, including cases brought before international courts.

Ongoing scrutiny of protests

Thunberg’s arrest is likely to add to broader debate in Britain over the limits of protest, particularly where demonstrations intersect with terrorism legislation. Legal experts say each case depends heavily on specific facts, including the wording of signs, the context of protests, and the intent of participants.

City of London Police said Thunberg remains on bail while inquiries continue. No court date has been publicly announced, and it remains unclear whether prosecutors will bring formal charges.