Netizens, many of them Chinese, bombarded Horton`s social media accounts after he called Chinese swimming rival Sun Yang a "drug cheat".
Rio de Janeiro: Thousands of vitriolic comments left on Australian swimmer Mack Horton`s Instagram account have been deleted by the Australian Olympic Committee (AOC).
Netizens, many of them Chinese, bombarded Horton`s social media accounts after he called Chinese swimming rival Sun Yang a "drug cheat" before they competed in Saturday`s men`s 400 metres freestyle final, demanding that he apologise.
By Wednesday, all comments - which numbered at least 200,000 on one photo post alone - had disappeared from Horton`s page.
"My staff are instructed to remove any comments that are offensive and in breach of the AOC`s Social Media Guidelines. Comments must not be disrespectful, threatening or in poor taste," AOC`s director of media & communications, Mike Tancred, told Reuters in an e-mail.
Instagram told Reuters it could not comment on specific user accounts. It has recently introduced new tools giving users more control over comments on their pages.
Censorship is common in China, whose users are prohibited from visiting certain websites by the government and often see controversial remarks on social media sites being deleted.
Facebook and Instagram are banned in China, meaning that mainland users have to access the sites by jumping the "Great Firewall" using a virtual private network.
That does not mean that users have stopped trying - screenshots of the message "mackhorton has turned off comments for this post" were posted on China`s social media sites.
The spat between Horton and Sun is turning into a battle of national media commentators and underlines how the issue of doping has become a defining issue for these Olympics.
Chinese state media reacted to Horton`s remarks by calling Australia "uncivilised" and "Britain`s offshore prison", while the Australian delegation said they would support Horton`s right to speak freely on the issue.
Sun, who finished second to Horton in the 400 freestyle, was revealed two years ago to have secretly served a three-month suspension for using a banned stimulant.
He said at the time the stimulant was in medication to treat a heart issue and did not enhance his performance.