Adam Peaty questioned the legitimacy of China’s victory in the men’s 4×100 metres medley relay as he suggested rival Qin Haiyang “should be out of the sport” over his doping past.

Qin and Sun Jiajun helped their nation claim gold but they were two of 23 Chinese swimmers who tested positive for the banned substance trimetazidine prior to the Tokyo Olympics and cleared to compete on the basis of a finding they had unknowingly ingested the drug via contaminated food.

The issue heavily overshadowed the build-up to Paris 2024 and appeared to lead to mistrust from several swimmers in the system, with Katie Ledecky and Caeleb Dressel expressing their misgivings, and Peaty joined the clamour on the final night of action in the pool as he singled out Qin for criticism.

As well as the recent furore, Peaty seemed to reference a New York Times allegation that Qin returned a positive test for a different performance-enhancing drug in 2017 – which was blamed on food contamination at the time – as a reason that he should no longer be allowed to compete.

“One of my favourite quotes I’ve seen lately is that there’s no point winning if you’re not winning fair,” Peaty said. “I think you know that truth in your heart.

“If you touch and you know that you’re cheating, you’re not winning. For me, if you’ve been on that and you have been ‘contaminated’ twice, I think as an honourable person you should be out of the sport.

“I don’t want to paint a whole nation or group of people with one brush, I think that’s very unfair. But there have been two cases of it and it’s very disappointing.

“The Americans have been very vocal. We didn’t want to get distracted with that. What I’ve said from the start is that it’s fraud. If you’re cheating, it’s fraud.”

Peaty, who raced alongside Oliver Morgan, Duncan Scott and Matt Richards, finished outside of the podium places in fourth although he insisted this was not a case of sour grapes.

While he is uncertain about his future in the sport, Peaty insisted every Team GB swimmer will use the row surrounding the Chinese swimmers as fuel for the fire ahead of the 2028 Olympics in Los Angeles – although he has called on anti-doping bosses to do more.

“We’ll use it to our advantage for the next four years, whether I’m there or not,” he said. “I know these boys will carry that and we’ll see how they do in four years’ time.

“But I think to the people that need to do their job – wake up and do your job. I think we have to have faith in the system. But we also don’t. I think it’s got to be stricter.

“It’s not about the podium because whoever’s in the race, I expect in my head has to be fair to be there. We did our best as a team.”

Peaty on Saturday described how he had had the “worst week” of his life physically after testing positive for Covid on Monday, having bagged silver in the men’s 100m breaststroke the night before.

Now 29, Peaty, who has struggled with injury and his mental health in the last couple of years, gave no indication whether this would be his last Olympics.

“Tomorrow is never promised and if my heart wants it my heart wants it and I will sign that contract with myself to do it,” Peaty added.

“That could be a long way away, but I think I’ve got to step away from the sport because it hurt too much this time.

“I’m going to take some time off everything and I don’t really know what the answer is. I’m taking time, if my family needs me they need me. I don’t know you can’t lie to your heart but if it wants it, it wants it.”