Rio de Janeiro: Australia has flatly rejected calls for an apology over swimmer Mack Horton's controversial comments about Chinese swimmer Sun Yang.

A war of words was sparked by Horton when he dismissed Sun as a drug cheat after beating him to claim the 400m freestyle gold medal on the opening night of the Rio Games.

Controversial comments: Mack Horton shows off his gold medal. Credit:Joe Armao

China has demanded an apology but Australian chef de mission Kitty Chiller says that won't be happening.

"Mack obviously has very strong views about the need for clean sport, as every single one of us does," she said.