Astarloza finished 11th in this year's Tour de France
Spanish cyclist Mikel Astarloza has protested his innocence after testing positive for blood-booster EPO.
Astarloza, who won stage 16 of the Tour de France, was suspended by the International Cycling Union following an out-of-competition test on 26 June.
"I haven't taken anything illegal," he told a news conference.
The 29-year-old also said there are reasons to doubt the "credibility" of the test, which was carried out in a Wada accredited laboratory in Madrid.
"I will do whatever it takes to find out where this supposed positive result came from," he added.
The rider and his team Euskaltel Euskadi have requested a B sample test, but regardless of the outcome Astarloza said he had lost faith in the system adding that it was "sporting suicide" to use drugs in this day and age.
If his B sample comes back positive then he faces a two-year ban from the sport.
Astarloza finished 11th in this year's tour and he is a previous winner of the Tour Down Under.