Amir Khan told Ringside that Lamont Peterson's failed drug test could never have been a mistake.
Khan was due to face Peterson in Las Vegas on May 19 - with the Bolton fighter out to avenge his controversial WBA and IBF light-welterweight defeat to the American in December.
However it emerged earlier this week that Peterson had tested positive for a banned steroid.
The news cast doubt over the rematch - with Golden Boy Promotions officially confirming that the bout had been cancelled - and Khan said boxers have a responsibility to watch what they put in their bodies.
"This could never be a mistake - even when I go to the doctors for a cough, I speak to my boxing doctor first and send him the name of the medicine I am taking," said Khan on Ringside.
"Lamont Peterson is a professional world champion fighter, he knows that testosterone is illegal and that steroids are illegal so why put those substances in your body?
"Every drugs cheat out there always comes up with an excuse - is that the best one he can come up with that he didn't know it was a drug?
"It looks bad for the sport and I think it is a good thing that we bought this random testing in because I would never have found out that he had taken anything if we didn't.
"I am very surprised this has happened because he seems like a really humble guy. He is very likeable and him and his trainer were very respectful. I don't know how he could face me after the first fight knowing - how could he call himself a world champion?
"That is what hurts me that he knowingly took this stuff. It looks bad for himself and he has disappointed America and disrespected his own fans. This sport of boxing is the king of sports."
Clean up boxing
Khan has called on the Nevada Boxing Commission to take further action against Peterson and hopes that he gets the chance to get his belts back
"The Nevada Commission have taken the licence off Lamont Peterson and they don't want him to fight in the next fight, so I think whoever I fight next they'll put the titles on the line or we still go through the process and we might get the titles back and the fight that we had last time will be a no-contest.
"I just hope that the commission come back with a decent result and they do something about this. If they let this go then other fighters will say it is okay to take testosterone and steroids.
"Let's clean the sport up. I would also like to thank Floyd Mayweather who picked up on this. Everyone thought that he was being crazy when he said he wanted fighters to have drug tests but look what has happened."
Khan is now aiming to get back in the ring this summer, although he is not sure who is next opponent will be.
"It is really hard because when you look through the division there is not really anyone left really," added Khan.
"We have offered a few names to HBO and to Sky - perhaps a rematch against Zab Judah or Marcos Maidana. Another guy is the WBC champion Danny Garcia, he boxed well against Morales and beat him.
"He is also on Golden Boy and I think that fight would be easier to arrange than if we went outside the stable.
"I am willing to take on anyone really."