Australia has barred Sun Yang, a Chinese Olympic swimmer, from training in the country amid a three-month ban for a doping violation. Sun had tested positive for trimetazidine, a banned stimulant, during a national swimming championship in May.

The ban was not publicly disclosed as China’s swimming federation worked to defend Sun, claiming he had taken the drug for a heart condition and did not plan to cheat. Last week, Michael Scott, a senior official at Swimming Australia met Sun's Australian coach Denis Cotterell and told him that the gold-medal winner would not be allowed in the country's pools. The Chinese government reportedly pays a bonus of $250,000 to Australian coaches for every Olympic gold medal won by its athletes, the Courier Mail reported

"I met Denis last Tuesday," Scott told Courier Mail, a Brisbane-based newspaper, adding: "As a result of that meeting and our policy, Denis has advised the Chinese swimming federation that Sun Yang will not be allowed to train at Miami (Swimming Club) any more or any of our podium centers. (Integrity) is foremost going forward. It was a very straight forward call, which Denis supported and has been acted upon already."

Scott also added that the authority was strengthening protocols on foreign swimmers and getting them to register with Australia's national anti-doping agency. The swimmers would also need to pay a fee to Swimming Australia to allow them to be tested during their stay in the country.

The 23-year-old Sun won the Olympic gold medal in 2012 by breaking Cotterell-trained Grant Hackett’s 1500m freestyle world record. And because the ban was kept under wraps, Sun was able to participate in September’s Asian Games in South Korea’s Incheon, where he won three gold medals, Reuters reported.

For a first breach of the doping code, swimmers are usually given a two-year ban by the World Anti-Doping Agency. This ban will be increased to four years from Jan. 1.