The Hardwicke Stakes at Royal Ascot on Saturday ended tragically when the winning horse, Thomas Chippendale, collapsed and died soon after passing the winning post.

Veterinarians attending the horse were unable to revive the horse after jockey Johnny Murtagh had dismounted. A post-mortem will be conducted but the suspected cause was a heart attack.

"I felt him wobble underneath me and jumped off him," Murtagh said.

"Then he lost his balance and went down. It is heart-breaking for everyone involved; he ran his heart out."

In a separate incident, the favourite, Ektihaam, slipped when rounding a bend at halfway, throwing his jockey, Paul Hanagan, violently to the ground.

Although Hanagan injured his shoulder he was able to stand up unaided and return to the weighing room. He was stood down from riding for the rest of the day by the racecourse doctor and was sent to hospital for X-Rays. Ektimaal returned unharmed.

Thomas Chippendale's death marred what had been a successful royal meeting for the late Henry Cecil's stable. Cecil's widow, Jane, took over the training license and saddled Riposte to win the Ribblesdale Stakes on Thursday.

Thomas Chippendale was owned by Sir Robert Ogden, who consoled Murtagh in a sombre winner's circle after the race, Odgen also had conciliatory words for the horse's groom, Louis Villareal, who was in floods of tears.

"The horse ran a brilliant race and then this happens," Villareal said. "This week has been very emotional for us and very hard, but we will keep fighting and doing our jobs."

A four-year-old colt, Thomas Chippendale moved into the lead approaching the final furlong before resisting Dandino and Universal to claim the 200,000 prize. He also won the King Edward VII Stakes at Royal Ascot 12 months ago.