Tommy Robinson has been arrested under anti-terror laws, according to his supporters, after a protest at which a film was allegedly screened in contempt of court.

His detention was made public in a post on his verified X account and follows a march led by Robinson and a counter-protest in central London on Saturday which attracted thousands of people.

A complaint was later made over a film which was allegedly shown to the crowd in breach of a High Court order, with police saying officers were making further inquiries.

Robinson, whose real name is Stephen Yaxley Lennon, also on Saturday afternoon posted a one hour 45 minute film on X, in which he said he had previously avoided publishing the video because he was “scared”.

It is unclear whether Robinson’s arrest is related to the film, which centres on the case of Jamal Hijazi, who was a schoolboy when he was assaulted at Almondbury Community School in Huddersfield, West Yorkshire, in October 2018.

A post on his X account on Sunday said: “We can confirm that Tommy Robinson has been detained by police using powers afforded to them under the Terrorism Act 2000.

“That’s right, you read that correctly, Tommy is being held by police using counter terrorism legislation.

“We will update you as and when we can.”

The Metropolitan Police said there was “no Met involvement” in reference to the post about Robinson’s arrest.

In response to a complaint about the film on X on Saturday evening, the Met said: “We did not know what films would be shown during the event. Organisers of protests are not required to share those details in advance. There is no power for us to compel them to do so.

“Officers on duty for the event couldn’t reasonably have been aware of civil proceedings ongoing in relation to a particular film, but having now been made aware we’re making further inquiries to determine what action we need to take.”

A group of around 70 demonstrators gathered outside Downing Street and later New Scotland Yard on Sunday in protest at the alleged arrest.

Some of the protesters made speeches and chanted Robinson’s name while others held banners and T-shirts that had a photo of Robinson with tape over his mouth with “#freetommy” written alongside.

One of the apparent organisers shouted from a bench beside the Scotland Yard sign: “Today they are attempting to assassinate Tommy Robinson and we must stop them.”

Several of the protesters said they did not know where Robinson was arrested.

Syrian refugee Mr Hijazi successfully sued Robinson in 2021 after he made false claims, including about Mr Hijazi attacking girls in his school.

The court also ordered an injunction preventing Mr Robinson from repeating the allegations he made against the then-teenager.

In August 2022, Robinson was fined £900 for failing to turn up at a High Court hearing to be questioned about his finances related to pre-trial costs in the case of around £43,000.

In June this year, the Attorney General’s Office (AGO) filed papers to begin potential contempt proceedings against Robinson over allegations he breached the court order from 2021.

He is due to appear at the High Court in London for a directions hearing in that case on Monday.