Police have been granted more time to question four serving members of the Army, including an Ipswich man, on suspicion of terrorism offences.

A 24-year-old from Ipswich, a 22-year-old from Birmingham, a 32-year-old from Powys, mid Wales, and a 24-year-old from Northampton, were detained by West Midlands Police on Tuesday as part of a “pre-planned and intelligence-led” operation, but the force said there was “no threat to the public’s safety”.

They were also arrested on suspicion of being a member of National Action, a proscribed neo-Nazi organisation.

One of the men is believed to have been serving in Royal Electrical and Mechanical Engineers (REME), while at least one other is in the Royal Anglian Regiment.

All four men continue to be held at a police station in the West Midlands. Detectives have a further five days to question the men, West Midlands Police said today.

The force said: “The men - a 22-year-old from Birmingham, a 32-year-old man arrested in Powys, a 24-year-old arrested in Ipswich and a 24-year-old arrested in Northampton - were detained on suspicion of being concerned in the commission, preparation and instigation of acts of terrorism under Section 41 of the Terrorism Act 2000.

“They were also arrested on suspicion of being a member of a proscribed organisation (National Action) contrary to Section 11 of the Terrorism Act.”

The arrests were carried out with West Midlands Counter Terrorism Unit in conjunction with the Welsh Extremism and Counter Terrorism Unit and the East Midlands Counter Terrorism Intelligence Unit.

All searches have been completed in connection with the arrests.

National Action, described by the Home Office as “virulently racist, anti-Semitic and homophobic”, became the first extreme right-wing group to be banned under terrorism laws in December 2016.

An entry for National Action in the official list of proscribed groups says it is a “racist neo-Nazi group” that was established in 2013 and has branches across the UK which “conduct provocative street demonstrations and stunts aimed at intimidating local communities”.

The proscription means that being a member of or inviting support for the organisation is a criminal offence carrying a sentence of up to 10 years’ imprisonment.