Tommy Robinson’s “racist invective” about a Syrian refugee who was filmed being attacked in a school playground led to the teenager and his family being targeted by far-right activists, the high court has heard.

A video showing Jamal Hijazi, then 16, being pushed to the ground and threatened with drowning at Almondbury school in Huddersfield provoked outrage and a flood of public sympathy after it was shared online in November 2018.

Robinson, 37, the English Defence League founder, whose real name is Stephen Yaxley-Lennon, later commented about the incident in two Facebook videos, claiming Jamal was “not innocent and he violently attacks young English girls in his school”.

He also claimed Jamal “beat a girl black and blue” and “threatened to stab” another boy at his school. Jamal “emphatically denies” the allegations, the court was told. The teenager is bringing a libel claim against Robinson over the comments at the high court in London.

At a preliminary hearing on Thursday, Mr Justice Nicklin was asked to determine the “natural and ordinary” meaning of Robinson’s statements.

Jamal’s barrister, Ian Helme, told the court that “the notorious far-right provocateur” Robinson has accepted that the statements were “very seriously defamatory” of Jamal. He added that Robinson’s videos led to targeting of the claimant and his family by far-right activists which forced them to leave the area.

Helme said the case served as a reminder that “sometimes words on social media have devastating, personal, real-world consequences”. He said the two videos, the first of which he said had been viewed more than 850,000 times within 24 hours, were “short, sharp videos designed for the social media age – they are viewable instantaneously and repeatedly”.

Helme submitted that Robinson’s comments meant that Jamal was “a violent individual who was part of a gang that committed numerous acts of violence against schoolgirls” and had “committed very serious violence against at least one schoolgirl”.

William Bennett QC, for Robinson, said his client did not deny that he had made serious allegations, adding: “He wanted to make serious allegations and bring them to the attention of the world.”

He argued in written submissions that the viral video “was interpreted on social media as an example of racist bullying”, which “led to a massive social media witch-hunt of the alleged assailant which ultimately caused him and his family to have to flee Huddersfield”.

Bennett added: “[Robinson’s] case is that when he posed the videos in issue, he was trying to present the other side of the story – that in fact the claimant had been violent towards other children and that there was a background to the incident which was not being talked about.”

He asked the court to find that the meaning of the comments was that “the claimant has committed acts of violence against children”, a meaning he said Robinson will prove to be substantially true.

At a previous hearing in November, Bennett said the case would come down to the “oral testimony of one witness against another”. He added that Robinson’s defence would focus on “those people who say they were assaulted by the claimant and the claimant’s denials that he assaulted them”.

Mr Justice Nicklin reserved his judgment.