Tommy Robinson said he was detained at Heathrow Airport in London for about three hours on Saturday under counter-terror border powers, with police seizing his phone.
Robinson, whose real name is Stephen Yaxley-Lennon, said on X that officers held him under the Counter-Terrorism and Border Security Act. The Metropolitan Police confirmed officers stopped a man in his 40s after he returned to Britain from Russia via Turkey.
Police said the man was interviewed, his communication devices were seized, and he was later released. The Metropolitan Police did not name Robinson in the statement.
Robinson’s detention followed a week in which he posted repeatedly about racist and anti-immigrant riots in Northern Ireland. The Guardian also reported that he was detained under Section 3 of the Counter-Terrorism and Border Security Act 2019.
The unrest in Belfast followed a viral video showing a stabbing in which a man lost an eye. A Sudanese man has been charged with attempted murder, and police have said they are not treating the attack as terrorism.
In the days after the attack, rioters targeted homes and businesses owned by ethnic minorities or foreign residents. The British minister for Northern Ireland described the violence as racist thuggery.
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Local politicians said far-right agitators online helped coordinate or promote the violence. Robinson had repeatedly tweeted about the unrest before his detention at Heathrow.