Five men were arrested in Cambridge, Banbury, Wolverhampton, Leicester and Stockport yesterday while a woman was held in Banbury on suspicion of being members of banned far-right group National Action.
All six are currently being quizzed at a police station in the West Midlands while a number of homes are being raided by police.
Police said the suspects, aged between 21 and 37, were detained under Section 41 of the Terrorism Act as part of a planned operation.
They were arrested on suspicion of being concerned in the commission, preparation and instigation of acts of terrorism, namely on suspicion of being a member of a proscribed organisation, National Action.
West Midlands Police said the men – a 26-year-old from Cambridge, a 21-year-old from Banbury, Oxfordshire, a 28-year-old from Wolverhampton, a 26-year-old from Leicester and a 24-year-old from Stockport – and a 37-year-old woman also from Banbury are being held on terror offences.
A spokesperson added: “The arrests were carried out with West Midlands Counter Terrorism Unit in conjunction with North West CTU, South East CTU, Eastern CTIU and EMSOU-SB (previously EM CTIU).
“The arrests were pre-planned and intelligence-led; there was no threat to the public’s safety.”
Home Secretary Amber Rudd said at the time: “National Action is a racist, anti-Semitic and homophobic organisation which stirs up hatred, glorifies violence and promotes a vile ideology, and I will not stand for it. It has absolutely no place in a Britain that works for everyone.”
National Action was made a proscribed terrorist organisation in December 2016, becoming the first extreme right-wing group to be outlawed in the UK.
In the months before the ban, National Action had praised terrorist killer Thomas Mair, who shot and stabbed the Labour MP Jo Cox to death in June 2016.
And the group adopted the phrase “Death to traitors” – which was said by Mair in court – as its motto.