Anderson Silva not only tested positive for Drostanolone metabolites in a Jan. 9 out-of-competition drug test, but traces of the banned substance Androstane were also found within the legendary champion's system, according to Nevada Athletic Commission (NAC) executive director Bob Bennett.

Drostanolone is a common form of anabolic steroid. Androstane is a form of endogenous steroid hormone. Both substances are banned according to World Anti-Doping Agency (WADA) code.

Silva, 39, defeated Diaz via unanimous decision on Jan. 31 at UFC 183.

According to Bennett, Silva was given out-of-competition blood tests on Jan. 9 and Jan. 19. An in-competition urine test was also administered on Jan. 31. Silva passed the latter test, according to Bennett, however results of the Jan. 19 test are still pending.

The Sports Medicine Research and Testing Laboratory at the University of Utah conducted the tests. The news was first reported by Yahoo Sports.

"I think it's very unfortunate," Bennett told MMAFighting.com's Ariel Helwani. "The UFC have made a tremendous effort to level the playing field in their fight against PEDs. Credit goes to them for doing the right thing based on principles and they continue to support our out-of-competition drug testing efforts.

"You can't lose sight of all the other athletes that do what they are supposed to do and fight cleanly. The UFC deserves a great deal of credit for supporting the PED challenge that we currently have. It's just unfortunate for all of us."

Bennett added that the NAC's objective moving forward will be to receive out-of-competition drug test results within one week's time, as this is the second such incident in recent weeks where out-of-competition test results were revealed well after the initial testing failure. UFC light heavyweight Jon Jones tested positive for cocaine metabolites in a Dec. 3 random test, however the results were not announced until Jan. 6, several days after Jones' blockbuster fight against Daniel Cormier.

"The time lapse is unacceptable," Bennett said. "We've made arrangements with the lab to make sure we get the results within seven days and they are working hand in glove with us on this."

Silva is expected to appear at a Feb. 17 commission meeting in Nevada, where he will likely be handed a temporary suspension, according to NAC chairman Francisco Aguilar. A full hearing for Silva is expected to take place at an NAC meeting in either March or April.

The UFC released the following statement regarding Silva's failed test on Tuesday.

"On February 3, 2015, the UFC organization was notified by the Nevada State Athletic Commission that Anderson Silva tested positive for Drostanolone metabolites on his Jan. 9 out of competition drug test. UFC's understanding is that further testing will be conducted by the Commission to confirm these preliminary results.

"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.

"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."