The far-right activist Tommy Robinson has been jailed for 18 months for contempt of court for repeating false allegations against a Syrian refugee, in breach of an injunction.

He was told that “nobody is above the law” by a judge who said the “flagrant” breaches had been done in a “sophisticated” way to ensure the false claims would achieve “maximum coverage”, reaching tens of millions of people.

Robinson, whose real name is Stephen Yaxley-Lennon, had shown no remorse and there was no realistic prospect of rehabilitation, said Mr Justice Johnson, who told Woolwich crown court on Monday: “All of his actions so far suggest that he regards himself as above the law.”

However, the judge allowed for four months to be removed from the sentence if Robinson “purged” himself by removing the false claims from social media accounts he controlled.

While two days had been set aside for the hearing, the court was told in the morning that Robinson had admitted contempt through 10 breaches of a high court order made in 2021, and which led to the solicitor general issuing two contempt applications.

The hearing was told that Robinson had in effect repeated all of the allegations that led to him losing a libel case brought by Jamal Hijazi, who had been filmed being attacked at a school in West Yorkshire.

Shortly after the video of the incident went viral, Robinson falsely claimed in Facebook videos that Hijazi was “not innocent and he violently attacks young English girls in his school”.

The false claims were repeated by Robinson in interviews with figures including Gareth Icke, son of the conspiracy theorist David Icke, and in a film made by Robinson. Entitled Silenced, it was viewed by millions of people as a result of being shared on online platforms including that of the misogynist influencer Andrew Tate.

Aidan Eardley KC, for the solicitor general, said: “The film is a substantial piece of work. It lasts about 90 minutes and is entirely devoted to the Hijazi story.”

Other breaches of court instructions included airing the film on screens during a rally that Robinson organised for his supporters in Trafalgar Square on 27 July.

The solicitor general, Sarah Sackman, said: “Those who breach court orders risk finding themselves in contempt of court. The sentence issued by the judge today confirms that no one should consider themselves above the rule of law.”

Rupert Lowe, a Reform UK MP, tweeted that he hoped Robinson would be given protection to ensure his safety in prison, adding that he would be raising concerns with the Ministry of Justice on behalf of constituents.

At the start of the hearing, Eardley said a “resolution” had been reached over the allegations.

When asked by Mr Justice Johnson whether he accepted he had committed the breaches, Robinson nodded and then replied: “Yes.”

Referring to Robinson by his real name, Eardley said the case was not about the far right figure’s political activities. “It’s a case about disobedience to an order of a court and an undermining of the rule of law,” he said.

The court was told by Sasha Wass KC, for Robinson, that he was a journalist and it was his “principles that have brought him before the court”. She argued for mitigation on the basis that her client had pleaded guilty “sooner rather than later” even though he previously failed to turn up at a hearing of the case in July.

Robinson was ordered to pay costs of £80,350.82 sought by the solicitor general. He was reminded by Mr Justice Johnson that he would still be subject to the injunction after his release and liable for sanction again if he breached it. The potential for early release after 14 months was dependent on, at the very least, removing Silenced from his social media accounts.

The anti-racism campaign group Hope Not Hate, which originally put together a dossier detailing how Robinson had breached the injunction, said: “Today’s verdict proves that even Lennon’s actions have consequences and goes some way to delivering justice for Jamal Hijazi.”