A kitchen porter at a prestigious public school has been arrested on suspicion of poisoning soup, the school said.

The 58-year-old man was questioned and released on bail after staff at Stowe School reported concerns to police last week.

The £27,000-a-year school, with former pupils including Sir Richard Branson, said the man was immediately suspended after the allegations emerged.

Police said the man was arrested on March 12 at his home near Brackley.

He was questioned on suspicion of administering poison with intent to endanger life or inflict grievous bodily harm.

Police said they could not detain him due to health reasons and released him on bail until March 29.

Detective Constable Vicky Ball, of Thames Valley Police, said: "Nobody has been harmed, but these are serious accusations. Our investigation is still in its early stages and forensic work is continuing."

Staff were carrying out "routine checks" before food was served to the pupils on March 11 when they became suspicious that the soup had been tampered with. Staff became suspicious after noticing a chemical smell in the soup.

Headteacher Anthony Wallersteiner said: "I would like to reassure parents that no pupils or members of staff were affected in the incident."

The school, which has 750 pupils aged between 13 and 18, said an email was sent to parents on Tuesday alerting them to the arrest.