The controversial Yang was in the spotlight in Gwanju on Sunday when Australia's Mack Horton refused to share the podium with Sun after he finished second in the 400m freestyle final.

Two days later British 200m co-bronze medallist Duncan Scott didn't shake Yang's hand or take part in the ceremony's photo shoot, prompting an angry reaction from Yang, who claimed gold after Lithuania's Danas Rapsys was disqualified for a false start.

Sun could be seen gesticulating wildly at Scott post-ceremony, with TV cameras capturing the Chinese champion saying: "You loser, I am winning".

Asked for her reaction to Sun's behaviour, triple Olympic 100m freestyle champion Fraser responded: "If I had been there, I would have kicked him in the backside."

Fraser thought Sun shouldn't even be competing in South Korea.

"He's got a Court of Arbitration (of Sport) hearing in September and I feel that (swimming's world governing body) FINA should have stepped him down until that court case is over," Fraser said.

"If he's proven not guilty that's fine, he can come back to swimming.

'We want a clean sport ... FINA have got to get off their backsides and do something about it."

Sun, who served a secret three month doping ban in 2014, faces a lifetime suspension if found guilty of the charges.

Horton, meanwhile, was issued with an official warning from FINA over his protest.

''He just didn't get on the podium to be with a drug cheat and I support that," Fraser said.

Australia's 2012 Olympic 100m hurdles champion Sally Pearson also backed Horton's stance.

"For him to take that stand, I salute him. I don't think many athletes would have the courage to do that," Pearson told Fox Sports.

Fraser added she was delighted with the performance of Ariarne Titmus, who upset five-time Olympic champion Katie Ledecky to win the 400m freestyle final.

"I've watched Ariane swim for the last three years. She's just amazing, she's just going on to to bigger and better swims all the time," she said.

Fraser was bullish about the Australia'n swim team's prospects at next year's Tokyo Olympics after conceding they didn't perform well at Rio de Janeiro in 2016.

"We've turned the corner and we're going to have a fantastic team in Tokyo. We've also got 14, 15, 16-year old kids you haven't heard of yet, but they will make a name for themselves after Tokyo."

Australian Associated Press