Trainer Paul Nicholls has confirmed that Cheltenham Gold Cup winner Kauto Star has been retired.

Questions had been raised over the future of the 12-year-old chaser and owner Clive Smith came to the decision to call time on the horse's racing career.

"We have had nine superb years with the horse but, after seeing him in his work these past few weeks, myself, Clifford and Dan were of the opinion that the time had arrived to retire him," Nicholls told Betfair.com.

"Of course, as owner, the final decision rested with Clive, but he agreed that the horse had done enough. In some ways I think we have to protect him from himself. And maybe ourselves, too."

Kauto Star clinched the King George VI Chase for a record-breaking fifth time this season.