The leaders of far-right party Britain First, Paul Golding and Jayda Fransen, have been arrested in Northern Ireland.
Golding, 35, was detained shortly after arriving at Belfast magistrates' court where he was accompanying his deputy, Fransen, 31, to her first appearance over behaviour during a rally in Belfast that allegedly intended to, or was likely to, stir up hatred.
Golding was arrested in connection with alleged offences relating to the same rally.
The Police Service of Northern Ireland (PSNI) said: "Detectives investigating speeches made at the Northern Ireland Against Terrorism rally on Sunday 6 August this year have arrested a 35-year-old man today, Thursday 14 December, in the Belfast area.
"He has been taken to Musgrave PSNI station for interview. There are no further details at this stage."
Britain First confirmed Golding's arrest to its followers on Twitter.
Fransen, from Penge, south east London, had appeared in court on Thursday (14 December) accused of "using threatening, abusive, insulting words or behaviour" during a speech delivered to about 50 people in Belfast back in August.
Fransen, who denies the charges, was released on bail and ordered to appear before the court again on 9 January.
Police had attempted to limit her use of social media as part of bail conditions, but the judge, Fiona Bagnall, denied their request. She instead told Fransen she must not go within 500 metres of any demonstration or parade in Northern Ireland.
Fransen was then arrested after leaving the court over social media posts she allegedly made from Belfast on Wednesday, police said.
The PSNI said: "Detectives investigating an incident at a peace wall in Belfast on Wednesday 14 December have arrested a 31-year-old woman in the Belfast area today."
She has been taken to Belfast city centre police station for questioning.
Her court appearance comes after a diplomatic row erupted between the UK and US last month when President Donald Trump retweeted anti-Islam videos posted by Fransen.
Theresa May criticised Trump's decision to share the far-right group's messages.
Who are Britain First?
Britain First was founded in 2011 by former members of the far-right British National Party (BNP) and has long been accused of causing unrest in British Muslim communities.
While their party insists it holds peaceful protests, its marches often result in clashes with local residents or anti-fascist campaigners. These include the party's so-called "mosque invasions" and "Christian patrols".
The party has also been accused of repeatedly spreading misleading videos online showing Muslims in a negative light.
An investigation by Press Association earlier this year found the group had posted at least 10 of these clips over a period of about seven weeks – receiving hundreds of thousands of views on Twitter and Facebook.