A promising young horse rider with hopes of competing for Britain at the 2012 London Olympics is in a coma after breaking her neck when her horse threw her.

Rosie Chinery, 18, is considered to be one of the most promising point-to-point jockeys and three-day event competitors, and had recently been selected for the British under-21 team.

Her grandfather Aubrey Chinery, 73, who runs a stable yard at Great Yeldham, near Halstead, Essex, said that he was awaiting news from Addenbrooke’s Hospital, Cambridge, where she is unconscious.

“She was on someone else’s horse, but she had ridden it in point-to-point before,” he said. “She was going up a hill very fast and the horse either had a heart attack or collapsed. It more or less stopped dead and catapulted her off. Whether the horse fell on her, nobody knows really — everyone was far away. The other riders got there quicker than people on foot after they saw it happen. They were fantastic.”

Simon Barnes: My perfect weekend

The Times columnist looks forward to seeing Twenty20 without Allen Stanford and hopes England's rugby players stay out of the sin bin

• Simon Barnes: My perfect weekend

• Simon Barnes: My perfect weekend

• Simon Barnes: My perfect weekend

Related Links

• Phillips sets sights on London 2012 success

• Rider killed under horse had Olympic ambitions

An air ambulance was sent to the scene of the accident, which happened during training on Wednesday, but paramedics found her in such a delicate state that they decided that she should go to hospital by road to avoid causing further injuries.

Her parents, Paul and Karen, are by her bedside.

Her grandfather described the accident as a tragedy. “The ambulance crew said it was touch and go whether they’d get her to hospital in time. She’s known throughout the country — I have had phone calls all morning. She’s hoping to get into 2012. She’s a great prospect. But she’ll be back if she can get through all this. She’s got great talent.”

A spokeswoman for British Eventing, which is the governing body for equestrian events, described Ms Chiney as a rising talent who had attracted the attention of selectors. She was one of about 30 people in the Young Riders scheme, from which six competitors are selected for events.

“She was a really, really talented rider,” the spokeswoman said. “She came seventh last year at Weston Park International. She achieved so much so quickly, so the selectors have been keeping an eye on her.”

Mr Chinery said that his grand-daughter had competed around the country since she was very young and had a large collection of trophies and rosettes.

He runs the stable yard with Ms Chinery’s mother. Ms Chinery has a younger brother, William, 15, who was also at the scene of the accident in Newmarket.

Members of British equestrian teams regularly sustain injuries during training and events. Zara Phillips broke her collarbone in a three-day event in the French Pyrenees in October when her horse fell jumping a fence on the cross-country course. In 2004 she was taken to hospital after being knocked unconscious in a fall at a national event at Lulworth, Dorset.