World Boxing Council

Whyte landed the WBC interim heavyweight title with a unanimous-decision win over Rivas in London on Saturday.

But Boxing Scene reported on Wednesday that Whyte had "tested positive for one or more banned substances" prior to the fight, which was allowed to proceed by the British Boxing Board of Control (BBBofC).

Whyte's promoter, Matchroom's Eddie Hearn, said in a short Twitter statement that Whyte was cleared to fight following "extensive" testing before the bout by the Voluntary Anti-Doping Association (VADA) and UK Anti-Doping (UKAD).

Parker was listed as one of five fighters to miss a test this year as part of the WBC's Clean Boxing Program administered by the Voluntary Anti-Doping Association.

Parker's promoter, Duco Events, confirmed the WBO world heavyweight champion missed the test after his win over Romanian Razvan Cojanu in May because of an extended holiday.

"Joseph extended his holiday following the Cojanu bout on May 6 and didn't update the Vada system of his change of plans.