Five people have been arrested on suspicion of being members of banned far-right group National Action.
Three men, a woman and a 17-year-old boy are being questioned on suspicion of being members of the organisation, which was proscribed a terrorist group in December 2016.
They were detained on Wednesday morning following a series of raids carried out by West Midlands Counter Terrorism Unit across the country. All five are being held at a police station in the West Midlands, the force said.
Those arrested include a 22-year-old man from Birmingham, a 23-year-old man from Halifax, a 22-year-old woman also from Halifax, a 28-year-old man from Birmingham and a 17-year-old boy from Nottingham.
A number of properties are being searched in connection with the arrests.
The neo-Nazi group responsible for a series of attacks and threats on prominent British Jews was banned in December 2016.
Home Secretary Amber Rudd labelled National Action as “racist, anti-semitic and homophobic” as she announced the move to ban the group in the UK.
The Community Security Trust had been among those backing legislation to make National Action the first far-right organisation to be proscribed under British terrorism laws.