Swimming's international governing body has issued a warning to Australian athlete Mack Horton over his controversial protest against Chinese rival Sun Yang.
Horton refused to share a medal podium with Sun at the World Aquatics Championships in South Korea on Sunday.
He has previously accused Sun of being a "drug cheat". Sun denies recent claims he violated doping protocols.
Governing body Fina also warned Australian officials over the protest.
"While Fina respects the principle of freedom of speech, it has to be conducted in the right context," it said, adding that athletes should not "use Fina events to make personal statements or gestures".
After claiming silver on Sunday, Horton stood apart from Sun and did not shake hands with him. He also declined to take photos with Sun, but posed beside Italian bronze medallist Gabriele Detti.
Horton had said he felt "frustration" after the race, adding: "I think you know in what respect... His actions and how it has been handled speaks louder than anything I could say."
Sun responded by telling reporters that "disrespecting me was OK, but disrespecting China was unfortunate".
Since the race, Horton's social media accounts have been flooded with messages of criticism and abuse by Sun's fans.
The response echoes a similar online backlash against Horton when he first publicly criticised Sun at the 2016 Rio Olympics.
The China Daily, a state-run English-language newspaper, wrote of the incident in South Korea: "Horton's behaviour was not an insult to Chinese athletes, but an insult to himself."
In Australia, meanwhile, fans and fellow teammates have largely expressed support for him.
An opinion piece in Sydney's Daily Telegraph by columnist Julian Linden said Fina's decision to warn Horton was "a slap in the face to clean athletes".
Sun served a three-month suspension in 2014 for testing positive for a banned stimulant trimetazidine, which he said had been for a heart complaint.
He faces a fresh hearing at the Court of Arbitration for Sport in September, after the World Anti-doping Agency appealed against a decision to clear him of a separate doping offence.
Reports have alleged that he avoided a drugs ban after destroying blood samples. Sun has denied the allegations.