SIGNAPORE AIRLINES FILE PHOTO

A British man is believed to have died and twenty three are injured after a Singapore Airlines flight from Heathrow hit severe turbulence and was forced to change course.

The 73-year-old may have had a pre-existing health condition, suffering cardiac arrest on board, according to the director of Bangkok airport, where the plane was diverted.

The man’s wife is being treated in hospital.

He described the incident as ‘chaotic’, saying that an internal investigation would be launched accordingly.

Most of those hurt are believed to have suffered head injuries.

Tracking data shows the plane was cruising at an altitude of 37,000 feet off the coast of Myanmar at around 9am BST when it quickly fell 6000 ft.

The Boeing 777-300ER was carrying 211 passengers and 18 crew on a flight which took off from the London Airport.

On a Facebook post, Singapore Airlines says it offers its “deepest condolences to the family of the deceased.”

The airline added that it is working with local authorities in Thailand to provide medical assistance.