Tensions flared in Rio after Australia's Mack Horton referred to Chinese swim star Sun Yang as a "drug cheat" (AFP Photo/Martin Bureau)

Sydney (AFP) - Swimming Australia's website has been under siege by cyber attackers, reports said Friday, after tough talking by gold medallist Mack Horton on doping suspicions inspired anger in China.

Tensions flared in Rio de Janeiro after Australia's Horton referred to Chinese swim star Sun Yang, who he beat to gold in the 400m freestyle, as a "drug cheat".

The dispute turned into a social media war, with China's state-controlled Global Times newspaper calling Australia a former British "offshore prison".

Users accessing the Swimming Australia home page were Friday greeted with a message saying the site was "checking your browser" before it functioned as normal.

But reports said the site was operating in an "under attack mode", with Swimming Australia checking every browser before allowing access.

Fairfax Media quoted a Swimming Australia spokesman saying the sporting body "won't be making any comment on this story at this time".

"Our complete focus is on supporting our athletes to achieve peak performance in their events in Rio," he said.

The incident comes days after Australia's national online census was shut down due to repeated denial-of-service attacks which attempted to overwhelm the site and force it to crash.