Anjem Choudary, a radical British Muslim preacher, was today arrested for allegedly promoting ISIS in the UK.
The Metropolitan police said in a statement that he and another man, Mohammed Rahman, had been arrested under section 12 of the Terrorism Act.
Choudary, 48, from Ilford, and Rahman, 32, from east London, both appeared at a short hearing at Westminster Magistrates Court on Wednesday to incidicate that they would plead not guilty to the charges.
They will remain in police custody until a further hearing on 28 August, the BBC reported.
Choudary and Rahman are accused of "inviting support for a proscribed terrorist organisation, namely ISIL, also known as ISIS or the Islamic State" between 29 June 2014 and 6 March, the statement said.
The charges come almost a year after the pair were arrested, in September 2014, by the Met's counterterrorism command, SO15, on suspicion of being members of a "proscribed", or banned, organisation. Both suspects were out on police bail while under arrest, but are now both in police custody.
Sue Hemming, head of special crime and counterterrorism at the Crown Prosecution Service, said in a statement: "Following an investigation by the Metropolitan police's counter-terrorism command, we have today authorised charges against Anjem Choudary and Mohammed Mizanur Rahman.
"It is alleged that Anjem Choudary and Mohammed Rahman invited support for [ISIS] in individual lectures which were subsequently published online."