London (AFP) - Jarrell Miller could miss out on a shot at Anthony Joshua's world heavyweight titles after the American produced an "adverse finding" in a drug-testing sample.
Miller, who is undefeated in his 24 professional fights, was due to take on the Briton at Madison Square Garden for the WBA, IBF and WBO titles on June 1.
However, both camps have confirmed the Voluntary Anti-Doping Association (VADA) had informed them that Miller had returned the results from a test on March 20.
"We have been informed by VADA that there has been an adverse finding in Jarrell Miller's sample collected on March 20th, 2019," Eddie Hearn, Joshua's promoter, tweeted.
"We are working with all relevant parties and will update with more details soon. AJ's preparation continues for June 1st at MSG."
Miller is expected to face a hearing before the New York State Athletic Commission to decide whether he will be allowed to fight.
"We are in the process of obtaining further information about VADA's finding and will have more to say soon on this developing situation," Miller's camp, Salita Promotions, said in a statement via Twitter.
"In the meantime Jarrell continues to train for his June 1 fight against Anthony Joshua."
Miller previously served a nine-month ban from the California State Athletic Commission after testing positive for methylhexaneamine when kickboxing in 2014.
During their promotional tour for the fight, Miller revealed that both fighters had agreed to between 10 and 12 weeks of drug testing in the build-up to the bout.
Joshua, during the London leg of the tour, said: "I am on (drug testing scheme) ADAMS whereabouts, they have to know where I am for an hour every day and could walk in anytime.
"They can turn up any time during the day and that is a lifetime commitment. I have been on that since 2012 and I pay £40,000-a-fight to be tested by VADA two times a week."