Queensberry Promotions have confirmed Joseph Parker failed a drug test on Oct. 25, the day of his fight against Fabio Wardley in London. The boxer has however denied that he took ‘any substance’.

Parker suffered a Round 11 stoppage defeat at London’s O2 Arena with Wardley, losing his status as WBO mandatory challenger for undisputed heavyweight champion Oleksandr Usyk.

Writing on Instagram, Parker said: “I want to address today’s news. Before my recent fight I took a voluntary test and have now been informed that it returned an adverse result.

“This came as a real surprise to me. I did not take any prohibited substance, I do not use performance enhancing drugs and do not support their use.

“I am cooperating fully with the process now underway, and I am confident the investigation will clear my name.”

“Thank you to everyone who has sent messages of support. It means a great deal to me and my family. When the investigation is complete, I will speak openly and answer questions.”

Parker’s promotional company Queensberry had also released a statement on Friday morning.

“The Voluntary Anti-Doping Association [VADA] last night informed all required parties that Joseph Parker returned an adverse finding following an anti-doping test conducted on 25 October in relation to his bout with Fabio Wardley,” Queensberry said in a statement on Friday.

“While the matter is investigated further, no additional comment will be made at this time.”

Parker had positioned himself for a potential fight against Usyk after six-straight wins including victories over Deontay Wilder, Zhilei Zhang and Martin Bakole.

However, he could face a ban depending on the outcome of the investigation.