Ullrich was one of dozens of cyclists implicated in an alleged doping network in Spain last year, which forced him out of competing in last year's Tour de France.

The 33-year-old, Germany's only winner of the world's most prestigious bike race, in 1997, claimed Monday he never once cheated in his career.

"Today I'm ending my career as a professional cyclist. I never once cheated as a cyclist," said Ullrich, who spent the latter stages of his career being dominated by American rival Lance Armstrong.

After being implicated in an alleged scandal dubbed 'Operation Puerto', notably alongside Italian Ivan Basso, last year Ullrich was sacked by his T-Mobile team during the race.