Jarrell Miller has denied "willingly" taking a performance enhancing drug after reports of a failed drug test ruined plans for a Las Vegas fight this month.
The American heavyweight has been removed from a scheduled fight against Jerry Forrest, with co-promoters Top Rank confirming that Miller would be placed on temporary suspension by the Nevada State Athletic Commission.
Miller was set to resume his unbeaten 24-fight career and has questioned how he could have received the reported positive test.
"This is something that was ingested," Miller told Fight Network. "We don't know if it was contaminated, but we're investigating as of right now. Me and my team are just working due diligently to get the facts 100 per cent straight."
Asked whether he had purposefully taken performance enhancing drugs, Miller said: "No, I have never ever willingly take a steroid for performance enhancement purposes. No.
"Did I take something for healing properties, for injury, yes I have. Before a fight to win a fight and during a training camp, no, I have never done that."
WBC president Mauricio Sulaiman has said that Miller was 'expelled' by the WBC for not enrolling in the governing body's drug testing program for three years.
Sulaiman told Sky Sports: "Miller specifically, he was expelled from the WBC, because he failed to enrol in the clean boxing program. Not once, but twice."
Asked if Miller could fight for a WBC title in the future, Sulaiman said: "I don't speculate. I don't like to - what if.
"What I can say is that he's been out of the WBC picture for three years, because we did not consider him to be eligible for rankings, because he did not enrol in the clean boxing program.
"When he was first ranked. We sent them the documents. He had three months to fill three pieces of paper, and he failed to do so. Then somehow they claimed they didn't have the papers, so we rang him again and sent them the paper, and he didn't submit twice, so he has been expelled from the WBC for three years."
The WBC's top 15 ranked fighters in each weight class are asked to take part in the 'clean boxing program', which requires random, year-round unannounced testing for performance enhancing drugs and other prohibited methods in a program to be administered by VADA.
Miller had tested positive for banned substances before a world title fight with Anthony Joshua last July, and Andy Ruiz Jr was instead brought in as a replacement for the British star's US debut in New York.
The 31-year-old is co-promoted by Dmitriy Salita, who is awaiting a final ruling from the NSAC.
In a statement at the weekend, Salita said: "I am disappointed. I was looking forward to July 9th and Jarrell's return to the ring. This news is shocking to me as well.
"Hopefully soon we will find out more facts. As [Top Rank promoter] Bob Arum said, we're all going to be guided by the decision of the Nevada Athletic Commission."