Mack Horton
Mack Horton of Australia celebrates winning gold in the final of the men's 400m freestyle on in the Rio 2016 Olympic Games on 6 August 2016 Adam Pretty/Getty

Chinese swimming officials have demanded an apology after Australian Olympic gold medallist Mack Horton called the defending swimming champion Sun Yang a "drug cheat". Horton's comments came as tensions rose between the two contestants in the build-up to the men's 400m freestyle final during the Rio 2016 games.

Reports suggested Yang had taunted and splashed Horton during an incident at the training pool. Speaking afterwards, Horton said it had been exaggerated in the press, but then went on to call his rival a "drug cheat".

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"It got played up in the media," said Horton, according to The Sydney Morning Herald. "He just kind of splashed me but I ignored him because I don't have time or respect for drug cheats. He wasn't too happy about that so he kept splashing me. I just got in and did my thing."

Sun served a three-month suspension in 2014 for testing positive for a banned substance, but has been cleared to compete. His fans bombarded Horton's social media accounts with a wave of abuse in response to the Australian's comments.

Horton narrowly edged out Sun during the 400m freestyle on 6 August, claiming gold in a personal best time of 3:41:55. The Australian Olympic Committee has said that Horton is entitled to express his opinion on "something he feels strongly about" and wished him good luck in the games.

Following his win, Horton defended his comments: "I used the words drug cheat because he tested positive. I just have a problem with athletes who have tested positive and are still competing."

However, China's swimming team manager Xu Qi said the comments had been "a malicious personal attack". Sun burst into tears after losing the race on Saturday (6 August), prompting "Sun Yang Don't Cry" to become the top trending hashtag on China's Weibo social media channel.

According to Xinhua news agency, Qi said: "We think his inappropriate words greatly hurt the feelings between Chinese and Australian swimmers. It is proof of a lack of good manners and upbringing. We strongly demand an apology from this swimmer."