PARIS (REUTERS) - Luxembourg's Andy Schleck called time on his short cycling career on Thursday, forced to retire at 29 by a knee injury suffered in the Tour de France this year.

"I'm obviously disappointed to end my career like this," he said in a statement released by his Trek team. "I would have liked to keep on fighting but my knee just doesn't allow it. Since my crash in the UK there has hardly been any progress. While the ligaments have healed, the damaged cartilage is another story.

"I have been working hard on 'rehabbing' the knee but came to the hard realisation that at the risk of irreversibly injuring it, this is the best course of action."

The highlight of Schleck's career came when he won the 2010 Tour de France, when he was promoted from second place after Spain's Alberto Contador was stripped of the title for doping.

A gifted climber, Schleck, the younger brother of his Trek team mate Frank, claimed another prestigious victory in the 2009 Liege-Bastogne-Liege one-day race.

He collected his last win in 2011 at the end of an impressive solo ride on the 18th stage of the Tour.

However, after sustaining a hip injury in the 2012 Criterium du Dauphine he was never able to regain his top form.

After coming back from his injury layoff, he took 20th place overall in the 2013 Tour de France after being unable to follow the leaders in the mountains.

He pulled out of this year's Tour with the knee injury in a crash in the opening days of the race.

Schleck never worked hard enough on his weak point, the time trial, so he did not get another real shot at grand tour glory which he seemed destined for when he finished as best young rider in the 2007 Giro d'Italia.

"Cycling has been my life for many years and I will need time to figure out what I'd like to do," Schleck said. "Luckily I can count on my family, friends, and Trek who have always supported me.

"I am very happy to have trained and raced alongside my brother and to have made some of the best friends that I have. I have always said that cycling is not the beginning and the end of my life.

"I have a wonderful girlfriend and a wonderful son. I'm excited to find out what lies ahead."