Serving British soldiers are among four alleged members of National Action, the banned neo-Nazi group, arrested on suspicion of preparing acts of terrorism.
The men – a 22-year-old from Birmingham, a 32-year-old from Powys, a 24-year-old from Ipswich and a 24-year-old from Northampton – were held on Tuesday.
The Ministry of Defence confirmed that “a number of serving members of the Army have been arrested under the Terrorism Act”.
West Midlands Police said the four men have been arrested on suspicion of terrorism offences.
A spokesman said they “have been arrested on suspicion of being concerned in the commission, preparation and instigation of acts of terrorism under Section 41 of the Terrorism Act 2000; namely on suspicion of being a member of a proscribed organisation (National Action) contrary to sec 11 of the Terrorism Act”.
All four men are being held at a police station in the West Midlands.
The arrests were carried out by police in conjunction with counter-terror units from the West Midlands, Wales and the East Midlands.
Several properties are being searched in connection with the arrests.
A police spokesman added: “The arrests were pre-planned and intelligence-led; there was no threat to the public’s safety.”
An Army spokesman said: “We can confirm that a number of serving members of the Army have been arrested under the Terrorism Act for being associated with a proscribed far right group.