Kell Brook is still furious from the revelation of Amir Khan’s positive test for a performance-enhancing drug.

The retired former welterweight champion from Sheffield, England, was left aghast by the news earlier this month that Khan popped positive for ostarine immediately after their last year, which Brook won by sixth-round stoppage.

Khan has accepted the conclusion from United Kingdom Anti-Doping that his body had trace amounts of ostarine, but he has maintained that the ingestion of the drug was unintentional and accidental, which UKAD finds credible. The testing agency slapped Khan with a less punitive, backdated two-year ban. (Drug cheats typically get a four-year ban). Khan, however, is retired and has no intention of fighting again.

Brook has found Khan’s justifications sorely lacking and has made it clear his animosity for Khan is back in full force. (The two set aside their differences after their fight.)

In a recent interview, Brook blamed Khan for putting the sport to shame.

Khan is the second prominent British boxer to test positive for a banned substance. Last October, welterweight Conor Benn was revealed to have tested positive twice, in separate tests, for clomifene. Benn has repeatedly maintained his innocence, despite butting heads with the British Boxing Board of Control over their investigation.

“I want this to be highlighted, because I’ve got three beautiful kids and it’s scary to know that he come in there, with this drug in him,” Brook told Boxing News. “It’s basically going in there with a knife in one hand and a gun in the other—in a fight. It’s not a fair fight.

“He’s going in there on drugs, and it brings an horrible taste in me mouth. These young fighters, and the people what respect Amir Khan, and look up to him—he’s putting it out there to young fighters that he’s on drugs, and it’s putting an horrible f------ name attached to the boxing game, and it’s happening too often. And it’s just disrespecting the sport—these fighters are taking drugs, and cheating, and it’s destroying this game, that they’re doing this. It’s horrible.”

Sean Nam is the author of the forthcoming book Murder on Federal Street: Tyrone Everett, the Black Mafia, and the Last Golden Age of Philadelphia Boxing.