An American spy on secondment to GCHQ was stabbed last week by an alleged terrorist in the town where the UK intelligence agency is based, it has been reported.

Counter-terrorism police have confirmed that a 29-year-old man was arrested on suspicion of terrorism offences after a woman was stabbed outside a leisure centre in Cheltenham last Thursday evening.

Officers have until Thursday to question him.

Counter-Terrorism Policing South East said the woman sustained “serious injuries”.

“She was taken to hospital for treatment, where she remains in a stable condition,” they said.

The Daily Mail reported that the victim, who has not been officially identified, works for US intelligence and had been seconded to GCHQ.

GCHQ declined to comment on the claims.

Counter-terrorism police said they could neither confirm nor deny the allegations.

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The woman had reportedly been in a car at the leisure centre car park when the suspect attacked her.

It happened just three miles away from the sprawling donut-shaped complex where GCHQ is headquartered.

The stabbing was initially treated as attempted murder before the suspect was re-arrested under terrorism legislation.

Assistant Chief Constable Richard Ocone, of Gloucestershire Constabulary, said: “I would like to reassure those living locally or visiting the county that we believe this was an isolated incident and we are not aware of any wider threat to members of the public. We are working closely with our partners in Counter Terrorism Policing.

“We appreciate that an incident of this nature may be concerning and we would encourage people to contact us via 101 with any additional information they may have about the incident.”