"I've been competing in this sport for a very long time," Silva said in a statement released by his manager, Ed Soares. "This is my 19th fight in the UFC. I have been thoroughly tested many times and have never had a positive test.
"I have not taken any performance enhancing drugs. My stance on drugs is and will always be the same. I'm an advocate for a clean sport.
"I'm consulting with my advisors right now to explore all of my options and intend to fight this allegation and clear my name. I will not make any further comments until my team advises me to do so."
The medical director of Brazil's governing body for mixed martial arts had said earlier Wednesday that he talked to Silva, and the Brazilian fighter denied taking steroids.
UFC said Tuesday the former middleweight champion tested positive in an out-of-competition test Jan. 9. The announcement came just days after Silva beat Nick Diaz in Las Vegas in his return to the cage after breaking his lower left leg 13 months ago.
UFC president Dana White said in a statement Wednesday that Silva for now would continue in his role as a coach for "The Ultimate Fighter: Brazil," adding that UFC will let the investigative process play out before deciding what action to take.
"Anderson Silva has been one of the greatest athletes this sport has ever seen," White said. "He has had a long and distinguished career in mixed martial arts. In his nine years with the UFC, Anderson has never tested positive for a banned substance. In light of this, we want to ensure that Anderson gets his due process and we will support him during this time."
In an interview with a Brazilian radio station, Marcio Tannure said Silva told him he is "disappointed" and "upset" with the news that he tested positive.
Tannure told Radio Band News that Silva believes there was "contamination" or a "mistake by the laboratory" that handled his test.
The doctor said Silva will request his "B" sample be tested.
Silva, 39, had tested positive for the steroid drostanolone during a random out-of-competition test administered by the Nevada State Athletic Commission on Jan. 9. NSAC chairman Francisco Aguilar confirmed the positive test to ESPN.com's Brett Okamoto. ESPN.com obtained a copy of Silva's lab report, which indicates he also tested positive for a second steroid, androstane.
Silva (34-6) defeated Diaz via unanimous decision at UFC 183 at the MGM Grand Garden Arena. The NSAC said results of the prefight test were not available until Tuesday morning, which is why the fight was not canceled.
Additionally, Aguilar informed ESPN.com that Diaz (26-10) tested positive for marijuana metabolites during a postfight drug test. Aguilar said exact results were unavailable but confirmed Diaz's results were above the allowable limit of 150 nanograms per milliliter.
According to Aguilar, Silva was tested Jan. 9, Jan. 19 and Jan. 31 -- all blood and urine tests. Results of the out-of-competition Jan. 19 test are currently unavailable.
Each fighter faces a potential fine and suspension. It marks the third marijuana-related offense for Diaz.
The NSAC's next scheduled meeting is Feb. 17. Silva and Diaz likely will be temporarily suspended at that time. Full disciplinary hearings will be scheduled for each.
The Associated Press and ESPN.com's Brett Okamoto contributed to this report.
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