LOS ANGELES — Canelo Alvarez’s rematch with Gennady Golovkin is off.

The Mexican star announced his withdrawal from the middleweight championship fight at a news conference on Tuesday at Golden Boy Promotions’ headquarters, almost a month before he was set to meet GGG in their May 5 return bout. The decision comes after Alvarez tested positive in February for the banned substance clenbuterol, throwing the highly anticipated fight into jeopardy.

The Nevada State Athletic Commission filed a formal complaint against Canelo last week seeking disciplinary action to be decided at an April 18 hearing in Las Vegas, where the fight was set to take place at T-Mobile Arena. The legal letter left little wiggle room for Canelo’s claim that the positive test was a result of tainted meat consumed at his home in Guadalajara, Mexico.

The complaint said that under Nevada rules, the athlete is responsible for what enters his system, whether intentional or unintentional. Alvarez was also temporarily suspended by the commission last month.

Golden Boy Promotions president Eric Gomez acknowledged that Alvarez likely wouldn’t have been cleared for the May 5 fight and even if he was, they need enough time to promote a “fight of this magnitude.”

“I am truly shocked by what has happened and I’ll admit this has led to suspicions about my athletic ability,” Alvarez, 27, said in a prepared statement translated by his attorney, Ricardo Cestero. “I have always been a clean fighter and I always will be a clean fighter.

“I want to apologize for all of the inconvenience that this has caused HBO, MGM, Tecate, Hennessy, all my other sponsors, the media and to everyone involved in the promotion of this event and especially to the fans whom I want to say I have not let you down. I respect the sport and I have always been a clean fighter.

“I have always done tests before my fights with VADA, these tests are voluntary and despite their being voluntary I have always agreed to do them and they always came back negative. I am a clean fighter. [The tests] showed small traces of clenbuterol.

“How can this happen if I didn’t intentionally take clenbuterol? Unfortunately, there is a public problem in my country of Mexico. Over the years many athletes of many sports, including cycling, soccer, football and boxing have tested positive. Contaminated meat is what caused this test (result).”

Clenbuterol was found in urine samples collected on February 17 and February 20, part of the Voluntary Anti-Doping Association protocol agreed to by both fighters. The anabolic agents promotes lean muscle mass and helps reduce fat, and its often injected into cattle in Mexico.

Francisco Vargas and Erik Morales were both promoted by Golden Boy when they tested positive for clenbuterol, and each Mexican blamed meat consumed in Mexico. Nonetheless, Gomez says Alvarez was never warned about eating the meat in his homeland.

Dr. Miguel Angel Nazul, he vice president of the Mexican Federation of Sports Medicine, said Tuesday that the levels were consistent with food contamination. “It doesn’t matter where you buy your meat or what social level you come from … it’s a problem that exists in Mexico,” Nazul said. Cestero said receipts were provided to the commission proving Canelo ate beef at restaurants in Mexico.

Alvarez said he’ll cooperate with the Nevada commission and undergo any additional tests they request to “prove without a doubt that I never intentionally ingested clenbuterol. I have nothing to hide. I want to be transparent and open during this process.”

Violators of the state’s anti-doping rules face a minimum one-year ban, but that penalty can be slashed in half for athletes who cooperate.

THE RING’s middleweight champion engaged in a thrilling battle with GGG in September that ended in a controversial draw. Each fighter was anxious to prove who really deserved to win, and hoped to prove it in the ring on Cinco De Mayo.

The first bout generated the third-largest gate in boxing history, and given the spirited nature of the, and the inconclusive result, the encore figured to do even better business.

But that will have to wait for now.

Golovkin still plans to fight on May 5 in Las Vegas and is seeking a new opponent. In the meantime, Canelo awaits his fate with the Nevada commission on April 18 and hopes to prove his innocence.

“It saddens me that people are accusing me of doing something that is improper,” Alvarez said. “I have alway been a fighter with integrity and I’m proud of my career, a career where I’ve never done anything illegal. From here on ou I will take increased precautions with future fights and will ensure this never happens again.

“I am truly disappointed and upset that I will not able to participate in the rematch with Golovkin. I’ve been training and I wanted to prove in the ring that I am the best middleweight in the world once and for all.

“I am sad and I feel powerless that I can’t make the rematch happen at this point.”

Mike Coppinger is the Senior Writer for RingTV.com. Follow him on Twitter: @MikeCoppinger