Bradley Wiggins will not defend his Tour de France title because of a knee problem forcing him to pull out of the cycling showcase.

The British rider withdrew before the 13th stage of the Giro d'Italia two weeks ago because of a chest infection and has not been able to train properly. Team Sky said Friday that Wiggins also has an "ongoing knee condition" and he will not be considered for the race, which begins June 29.

"It's a huge disappointment not to make the Tour. I desperately wanted be there, for the team and for all the fans along the way — but it's not going to happen," Wiggins said in a team statement. "I can't train the way I need to train and I'm not going to be ready. Once you accept that, it's almost a relief not having to worry about the injury and the race against time."

Wiggins became the first British rider to win the Tour last year. In an astonishingly successful year, he also won the Paris-Nice stage race, Tour de Romandie, the Dauphine Libere and took the Olympic gold medal in dominant fashion in the time trial.

"It's a big loss but, given these circumstances, we won't consider him for selection," Sky's team principal Dave Brailsford said. "It's incredibly sad to have the reigning champion at Team Sky but not lining up at the Tour. But he's a champion, a formidable athlete and will come back winning as he has before."

With Wiggins out of the Tour, last year's runner-up, Chris Froome, will become the undisputed team leader. Sky had already said that Froome would be its team leader at this year's Tour, although Wiggins had indicated he might try to ride for victory if he were in contention toward the end.

Wiggins was looking to follow up his Tour success with a Giro win until his bid was derailed by illness. Although his chest infection has cleared up, team doctor Richard Freeman says there are still concerns over his knee.

"However, further medical investigations on the knee injury that we were managing at the Giro showed the condition was more significant than we thought," Freeman said. "It has needed intensive treatment and, whilst it will be fully resolved, Bradley now needs to rest completely for five days before a gradual, return to full training over a period of two to three weeks."

Wiggins had to withdraw from the 2011 Tour early on after breaking his collarbone in a crash. He has promised to come back stronger from this latest setback.

"I've been through this before, when I broke my collarbone, so I know how it works. I'll get this sorted, set new goals for this season and focus on those," Wiggins said. "This team has so many riders in great shape, ready for selection and we set incredible standards for performance which shouldn't be compromised. We need to have the best chance to win."