Former Ultimate Fighting Championship middleweight kingpin Anderson Silva tested positive for banned substance, the UFC announced Tuesday.

According to UFC, a random drug test conducted by the Nevada State Athletic Commission on Jan. 9 found traces of steroids drostanolone and androstane in Silva's urine sample. He was also tested on Jan. 19 and 31, but NSAC has yet to release the result of the pre-fight examination.

Silva, who was coming off a long layoff after sustaining a gruesome left leg injury, scored a unanimous decision win against Nick Diaz at UFC 183 main event on Saturday night at MGM Grand Garden Arena in Las Vegas. According to ESPN, UFC obtained the results of the tests on Tuesday, which was the reason why the fight between Silva and Diaz still pushed through on Saturday.

The promotion expressed disappointment in Silva's failed drug test in a statement released Tuesday.

"Anderson Silva has been an amazing champion and a true ambassador of the sport of mixed martial arts and the UFC, in Brazil as well as around the world. UFC is disappointed to learn of these initial results," UFC said in a statement. "The UFC has a strict, consistent policy against the use of any illegal and/or performance enhancing drugs, stimulants or masking agents by its athletes."

Silva has yet to issue an official statement, but Marcio Tannure, medical director of Brazil's mixed martial arts governing body, said the 39-year-old denied using steroids before his victory against Diaz. Tannure told reporters that a disappointed Silva believes there was contamination or the laboratory made a mistake in testing his urine sample. The doctor said that Silva's camp will request the former middleweight champion's B sample be tested as well.

Meanwhile, Diaz is also facing sanctions and penalties after testing positive for marijuana metabolites during a drug test following his loss to Silva. Reports indicated that amount of marijuana metabolites were above the 150 ng/ML allowable limit.

The NSAC will conduct a meeting on Feb. 17 to discuss sanctions for both Silva and Diaz. Both fighters are expected to face fines and suspension for their actions.

Diaz also tested positive for marijuana in 2007, which led to a six-month suspension, and in 2012, which merited a one-year ban from NSAC. Silva, on the other hand, has never tested for banned substance before.

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