A senior member of the United States Army has been arrested near Gloucester on suspicion of espionage offences linked to Russia, British counter-terrorism police have said.

The 41-year-old man, who has not been named, was arrested on Tuesday 10 November by officers from Counter Terrorism Policing, working closely with US authorities, the US military and the FBI.

He was arrested on suspicion of offences under Section 1 and Section 3 of the National Security Act 2023. Section 1 covers obtaining or disclosing protected information, while Section 3 covers assisting a foreign intelligence service. The Metropolitan Police said the country to which the allegations relate is Russia.

The man remains in custody at a London police station. Officers are carrying out searches at two locations in Gloucestershire as part of the investigation, which is being led by Counter Terrorism Policing London.

Arrest described as significant

Deputy Assistant Commissioner Vicki Evans, senior national coordinator for Counter Terrorism Policing, described the arrest as significant. The investigation is not linked to any other ongoing Counter Terrorism Policing investigations, police said.

FBI Director Kash Patel said the arrest involves allegations of espionage, adding that it was of the utmost concern to the United States and its allies.

Brigadier General Sean Stinchon, commanding general of US Army Counterintelligence Command, said the soldier was a senior soldier entrusted with sensitive information. He said the alleged conduct was a sobering reminder that insider threats are real and persistent.

What the National Security Act covers

The National Security Act 2023 replaced parts of the Official Secrets Acts of 1911 to 1989 and gave police new powers to deal with state threats. Section 1 makes it an offence to obtain or disclose protected information, while Section 3 makes it an offence to engage in conduct that assists a foreign intelligence service.

The Act also created new police powers, including detention of suspects for longer periods than under ordinary arrest powers, reflecting the complexity of state-threat investigations.

No charges yet

No charges have been announced, and the man has not been named by police. He was detained under the National Security Act 2023, and enquiries continue.

The arrest is a rare public example of a serving member of the US armed forces being detained in Britain on suspicion of offences under the National Security Act, which came into force to replace older official secrets legislation and to give police wider powers to deal with state threats.

Police have not given further details of the alleged conduct, the locations being searched, or how long the investigation had been running before Tuesday's arrest.