SCOTS IndyCar racer Dario Franchitti has announced his retirement after breaking his spine, right ankle and suffering concussion in a horrific crash last month.

The Bathgate-born three-time Indianapolis 500 winner revealed the news in a statement.

Franchitti, 40, said he had no option but to retire after doctors told him he must hang up his racing gloves.

He suffered the serious injuries on the last lap of the an IndyCar race in Houston, Texas.

He struck a car in the middle of the track and went flying into a fence in an accident that most observers thought he was lucky to survive.

Franchitti recently underwent two surgeries on his ankle and is now back in Scotland, where he owns a £3.8million home in Port of Menteith, Stirlingshire.

He said: "One month removed from the crash and based upon the expert advice of the doctors who have treated and assessed my head and spinal injuries post accident, it is their best medical opinion that I must stop racing.

"They have made it very clear that the risks involved in further racing are too great and could be detrimental to my long term well-being. Based on this medical advice, I have no choice but to stop."

He later posted a poignant tweet - above a photograph of himself next to one of his racing cars - with the words "A sad day but I'm eternally grateful... " It appeared to be a reference to the dangers of the sport, which have claimed a number of lives including fellow British driver Dan Wheldon.

Franchitti won three consecutive titles from 2009 to 2011, and two of his three Indy 500 wins. However, he never raced in Formula One despite his success in America.

Although his marriage to the Hollywood actress Ashley Judd ended in January, she went to his bedside in hospital after the accident.

Franchitti scored 31 victories in IndyCar.

His team boss Chip Ganassi said: "Dario Franchitti has done so much for Target Chip Ganassi Racing, so it will be very disappointing to not see him in our cars next season,

But simply put, Dario is a motorsports legend and will be sorely missed on the race track by everyone in the paddock and in the stands. His contributions to the sport of motor racing are too many to list, but I can tell you that they go way beyond what he has done on the track."