Okolie (23-1, 17 KOs) was slated to box home hopeful Yoka (15-3, 12 KOs) in a 12-round contest, headlining Queensberry's latest foray into Europe after success with Agit Kabayel in Germany on January 10.

The promotion shared a statement on social media, which read:

"Last night, the Voluntary Anti-Doping Association (VADA) informed Queensberry that Lawrence Okolie returned an adverse finding following an anti-doping test conducted ahead of the show in Paris this Saturday. A further update regarding the event will be made in due course."

Okolie has since responded to the news on Instagram with an image lying down and his left arm strapped with kinesiology tape isolated, accompanied by a caption which reads:

"Before anyone starts imagining the worst, following my bicep[s] injury last year, I sustained an elbow injury on the same arm during this camp. I had a treatment on it and now we are here. I truly hope sense prevails.

"I will of course be fully cooperating with all relevant authorities and I'm confident any investigation will clear my name. I won't be making any further comment at this time. Thank you for all your support and see you soon."

Both returned with knockout victories in Nigeria against overmatched opposition on December 21 before agreeing terms to fight, aware the divisional landscape necessitated a marquee win as world titles will likely fragment again.

Okolie is the WBC's No. 1 contender for Ring and unified champion Oleksandr Usyk's title he'll defend against Rico Verhoeven on May 23. Kabayel (27-0, 19 KOs) holds the interim strap.

A WBC junior middleweight title eliminator between Queensberry's new acquisition Bakary Samake (19-0, 11 KOs) and Ermal Hadribeaj (22-0-1, 8 KOs) is the card's big attraction outside the main event, while Irish heavyweight talent Adam Olaniyan was announced as a late-notice addition to the bill last weekend.

It is unclear whether Samake-Hadribeaj will be elevated to main event or if the card will be scrapped altogether. The Ring has reached out to Queensberry for confirmation.