The Metropolitan Police said a man in his 70s - who they did not name - was arrested in Southwark, south London, in the early hours of Sunday.

The 74-year-old anti-vaccine campaigner is the brother of the former Labour leader Jeremy Corbyn.

In a video on Telegram, he said: "I am out from Charing Cross police station, just released on a trumped-up charge of... encouraging people to commit arson, and I am released pending further investigation without any bail conditions."

Before the arrest, a clip shared widely on social media showed Mr Corbyn addressing a rally in London against COVID restrictions and seemingly taking aim at MPs who voted in favour of Plan B restrictions.

The Met said in a statement before the arrest: "We are aware of a video on social media in which people were encouraged to burn down MPs' offices. It is being assessed and enquiries are ongoing."

In the video, Mr Corbyn refers to his brother voting against Plan B, suggesting it was shot on 15 December, the day after they were passed by a majority in the Commons.

He says: "We've got to hammer to death those scum, those scum, who have decided to go ahead with introducing new fascism.

"We've got to get a list of them, we can get lists of them on websites, and if your MP's one of them, go to their offices, and well, I would recommend burning them down.

"But I can't say that on air, I hope we're not on air."