The Chinese Swimming Association (CSA) has defended the three-month ban handed out to world and Olympic swimming champion Sun Yang for a doping offense.

The CSA released a statement on Tuesday saying it believed Sun had made a mistake but never intended to cheat.

“Sun took the drug without an intention to improve his ­result, but both he and the ­Zhejiang swimming association had made mistakes,” said the statement.

Sun, who competes for the Zhejiang swimming association, secretly served the suspension earlier this year after testing positive for the banned stimulant trimetazidine during the Chinese national championships in May.

The China Anti-Doping Agency could have imposed a longer ban but said it decided on three months because Sun had been given medication by a doctor to treat a heart issue and was unaware it had been ­added to the World Anti-Doping Agency’s banned list this year.

“We believe Sun did not intend to cheat,” said Xu Qi, team leader of the Chinese national swimming team.

A news conference on Sun’s ban was abruptly canceled on Tuesday, reports said.

Swimming’s world governing body FINA issued a brief notice confirming the three-month ban and also a 12-month suspension that was handed out to Sun’s doctor.

Sun served his suspension in time to represent China at the Incheon Asian Games in South Korea in late September, where he won three gold ­medals.

But news of the ban was only announced on Monday, prompting questions as to why it was not released earlier.

In China, where Sun is regarded as a national hero after winning two gold medals at the 2012 London Olympic Games, the media were looking for answers.

The People’s Daily raised several questions in a commentary.

The paper asked why Sun did not declare his medication to the doping control officer and why star athletes “still do not understand the rules.”

“Perhaps society cannot ­demand that public figures maintain excellence in everything, but to ask that public figures pass every test in every undertaking, that standard is not too much,” the paper wrote.

“Clearly Sun Yang has shortcomings and those closest to him have not helped him ­improve.”

On Sina Weibo, the hashtag “Sun Yang’s punishment for doping” had been viewed more than 114 million times by press time.

The Olympic Council of Asia, which runs the Asian Games, has said it has no plans to strip Sun of his Asiad gold medals despite being unaware of the doping incident until Monday.