A picture taken with an underwater camera shows Australia's Mack Horton (L) and China's Sun Yang (C) compete in the Men's 400m Individual Medley Final during the swimming event at the Rio 2016 Olympic Games at the Olympic Aquatics Stadium in Rio de Janeiro on August 6, 2016. (Xinhua)

The International Olympic Committee (IOC) said it will look into the unfriendly comment Australian swimmer Mack Horton made on Chinese rival Sun Yang before it gave any comment.

IOC spokesperson Mark Adams said on Sunday that he did not konw the incident until reporters told him that Horton called defending 400m freestyle champion Sun a "drug cheat" before and after the 400m freestyle final.

"I didn't know the incident. I need to look into it," said Adams.

Sun missed the 400m title by the length of a finger tip behind Horton who clocked 3 minutes, 41.55 seconds in the Rio Olympic swimming final.

After the race, Horton was asked to give an explanation why he called him that way.

Sun was banned three months in 2014 for testing positive for trimetazidine which he used to treat his heart problem for years and failed to report for a theraputic exemption to the anti-doping authorities when the drug was put in the WADA banned substance list in 2014.

"I used the words drug cheat because he tested positive,' he said. "I just have a problem with athletes who have tested positive and are still competing."

Horton's hostility already showed early in the practice when Sun tried to greet him and Horton ignored and later telling reporters "Sun splashed me to say hello, and I didn't respond because I don't have time for drug cheats."

Sun defended himself and said he would ignore Horton's "trick".

"I am clean. I think every single athlete who is able to compete at the Olympic Games deserves respect. It is unnecessary to disturb an opponent with such little tricks," he said.

Australian swimming is looking to save their image following a disappointing show at London 2012 when they didn't bring home a single individual gold for the first time since 1976.

It was later found out that members of the swim team took the sleeping tablet at a pre-Games camp and star Grant Hackett is reported to seek treatment last year for addiction to the prescription drug zolpidem, sold as Stilnox in Australia.