Greta Thunberg has been arrested at a demonstration in support of the Palestine Action protesters who are on hunger strike in prison, according to the Prisoners for Palestine protest group.

The 22-year-old activist was detained in the City of London after attending the scene of the early-morning demonstration on Fenchurch Street.

In a video shared by the group, she could be seen holding a sign reading "I support the Palestine Action prisoners" and "I oppose genocide".

City of London Police said a 22-year-old woman was arrested for displaying a placard in support of a proscribed organisation, in this case Palestine Action, contrary to Section 13 of the Terrorism Act 2000.

The force said officers were called to the area at about 07:00 GMT after hammers and red paint were used to damage a building.

A man and a woman were also arrested on suspicion of criminal damage after they "glued themselves nearby", police said. Specialist officers worked to release them before taking them into custody.

PA Media Greta Thunberg inside a police vehicle, looking through a partition, with police officers visible in the foreground.PA Media

Ms Thunberg has been a prominent voice in Europe's pro-Palestinian movement

The Prisoners for Palestine protest group said it staged the demonstration outside the offices of Aspen Insurance, which it claimed provides services to Israeli-linked defence firm Elbit Systems.

Palestine Action was proscribed under UK terrorism legislation earlier this year, making it a criminal offence to support or express support for the group.

Police said inquiries were continuing.

Ms Thunberg, who first came to prominence as a child climate activist, has been involved in several demonstrations in support of the Palestinian cause.

She described the activists on hunger strike as "political prisoners" in a video posted on her Instagram on Monday, adding the UK government should meet their demands to be released from custody and for charges to be dropped.

Protesters targeted an office in the City with red paint

The protest comes after several imprisoned Palestine Action activists, including one who has refused to eat for 52 days, have been taken to hospital in recent days.

Since the hunger strike began on 2 November, a total of seven prisoners have been taken to hospital.

Kamran Ahmed, 28, who was being held at Pentonville Prison in north London, and Amu Gib, 30, who was being held at HMP Bronzefield in Surrey, have both been admitted to hospital in the past week.

Prisoners for Palestine previously said Mr Gib's health had "deteriorated rapidly" since joining the hunger strike on 2 November, and the activist now needed to use a wheelchair.

A legal firm representing the hunger strikers has said it submitted a pre-action letter on Monday against the Justice Secretary David Lammy.

The letter outlines the group's intention to initiate legal action.

Andrew Mountbatten-Windsor is understood to have voluntarily surrendered his gun licence after a visit from the Metropolitan Police.

Officers attended the former prince's Royal Lodge residence in Windsor last month, ahead of his expected house move in the new year.

A Met Police spokesperson said: "On Wednesday, 19 November, Metropolitan Police firearms licensing officers attended an address in Windsor to request that a man in his 60s voluntarily surrender his firearms and shotgun certificate."

The force said the certificate was surrendered but did not comment further.

It is not clear why the former prince - a known hunting enthusiast - gave up his licence, but the decision means he can only use or transport his guns if supervised.

Surrendering a certificate does not mean the individual will not have access to their firearms.

Andrew is expected to move to Norfolk in the new year, after he was stripped of his titles over his links to the late paedophile financier Jeffrey Epstein.

The former prince will move to an undisclosed property on the Sandringham estate, which is privately owned by his brother, King Charles III.

In October, Buckingham Palace said the move would take place "as soon as possible and practicable".

Andrew's connection to Epstein came under scrutiny again last week after a photo of him lying on the laps of women was released by the US government as part of the Epstein files.

The King's brother was one of many well-known figures to be pictured in the files, and appearing in them is not evidence of a crime. Andrew has always denied any wrongdoing in relation to Epstein. (BBC)

Andrew Mountbatten-Windsor gives up gun licence after police request (BBC)