Kell Brook has described as “scary” the knowledge that he fought Amir Khan on the day Khan failed a drugs test.

Khan, who retired from boxing in May 2022 – three months after being stopped in the sixth round by Brook – is serving a two-year ban after testing positive for the banned substance ostarine, which according to UK Anti-Doping (UKAD) is designed to have similar effects to testosterone.

The 36-year-old accepted that he broke anti-doping rules but said that he had not done so intentionally, and an independent tribunal accepted his argument, and therefore ruled out “deliberate or reckless conduct”.

Brook, however, is regardless disturbed to have learned that Khan’s performance could have been enhanced by the presence of a banned substance that night in February 2022 – one he’d previously found cathartic following years of a bitter rivalry – and revealed that it has made him fear for the future of his sport.

“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,” he 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 fucking 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.

“These fighters, from [Sugar Ray] Leonard days; [Marvin] Hagler; [Tommy] Hearns – all these fighters, these clean fighters – and these days it’s just getting tarnished with these drug cheats, and it’s putting a fucking horrible name on the game, what’s been beautiful and lovely, and given the fans and the fighters exciting nights. It’s just, horrible.

“I’m still a bit numb from it. He was the one that wanted all this drug testing in place. With the breaking news, and me finding out after everyone else – it’s been over a year since the fight happened, and nobody phoned me [to say], ‘He failed a drug test after the fight’. I’m scratching my head about. However it happens, Ben [Shalom], the promoter, UKAD; the [British] Boxing Board [of Control]. Nobody’s contacted me, in a fight – someone failing a test – what I was involved with. It just baffles me.

“The respect I had for Amir Khan has completely gone out the window. Because it makes me put into perspective – how long has he been on these drugs? I’m still waiting – it’s still fresh – and I’m still thinking, ‘What’s he gonna come out with? What is the reason? Why is it in his system?’ He failed a drugs test. I’ve got mixed emotions, at the moment, about it, but all I know is he failed a test and I were fighting him in that fight.”

Ostarine is also listed on the World Anti-Doping Agency’s (WADA) 2022 Prohibited List as an anabolic agent and is prohibited in sport at all times. Khan was notified about the adverse finding – from February 19, 2022 – on April 6, 2022, and issued with a provisional suspension from all code-compliant sport.

“It makes me think – ‘cause I hit him with some big heavy shots in that fight,” said Brook, also 36. “Even after, I said to Dom [Ingle, my trainer], ‘I don’t know how he’s stood on his feet that long’, to be honest with you, ‘cause I hit him with some nice shots and he still stood there, so it makes me think, ‘What’s this stuff he’s on? Could he just get through it better with this stuff in him?’ That’s what it’s made me think. If not, I reckon I could’ve flattened him in round one.”