Tommy Robinson has been remanded in custody after handing himself in at a police station in Folkestone, Kent.
Robinson, 41, was charged with one count of failing to provide the PIN to his mobile phone under Schedule 7 of the Terrorism Act 2000.
He will appear at Westminster Magistrates' Court on 13 November over the charge but has been remanded in custody ahead of a separate contempt of court case on Monday.
Robinson, whose real name is Stephen Yaxley-Lennon, was due to lead a rally in London on Saturday.
Earlier today he spoke to supporters outside the police station, where he told them: "I'll see what happens mate, I don't expect to come back out there."
A man in a grey jumpsuit went with him to the station carrying a blue holdall.
A High Court judge issued a warrant for the former English Defence League (EDL) leader's arrest after he failed to appear for a contempt of court hearing at the end of July.
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He left the country the day after leading a protest in central London and hours after being released on unconditional bail by Kent Police, who arrested him at the Channel Tunnel at Folkestone under Schedule 7 of the Terrorism Act 2000.
The law allows police to stop anyone passing through a UK port "to determine whether they may be involved or concerned in the commission, preparation or instigation of acts of terrorism".
Robinson, who flew back to the UK last weekend, is facing a possible jail sentence over the contempt of court claims at a two-day hearing at Woolwich Crown Court.
It's alleged he breached a 2021 High Court ruling, which ordered him to pay £100,000 in damages, as well as legal costs, and barred him from repeating libellous allegations against a Syrian refugee who successfully sued him.
He is accused of repeatedly breaching the order, including by airing a film at the July protest in Trafalgar Square and in interviews between February and June 2023.
Robinson's supporters are due to hold a demonstration on Saturday, which is expected to be met by a counter protest organised by Stand Up To Racism.
The Metropolitan Police said there will be a significant presence to keep the two groups apart.
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