Chinese Olympic swimmer Ye Shiwen has denied taking performance-enhancing drugs, after smashing a world record at the London Olympics.

Ye Shiwen, 16, won gold in the 400 m individual medley after breaking her personal best by at least five seconds.

She swam the last 50 m quicker than the men’s champion, prompting leading US coach John Leonard to describe her performance as “disturbing”.

There is no evidence against her and all medal winners are drug-tested.

She is due to race in the final of the 200m individual medley later on Tuesday.

Coach John Leonard, executive director of the World Swimming Coaches Association, said her performance reminded him of the East German women swimmers in the 1980s who were doping on a systematic basis.

“History in our sport will tell you that every time we see something, and I will put quotation marks around this, unbelievable, history shows us that it turns out later on there was doping involved,” John Leonard told the UK’s Guardian newspaper.

Chinese Olympic swimmer Ye Shiwen has denied taking performance-enhancing drugs, after smashing a world record at the London Olympics

China’s swimming team was repeatedly hit by doping scandals in the 1990s.

Seven swimmers tested positive for drugs in the 1994 Asian Games, and four years later four Chinese swimmers failed pre-tournament drug tests before swimming world championships in Australia.

But Ye Shiwen denied the allegations, telling reporters: “My results come from hard work and training and I would never use any banned drugs. The Chinese people have clean hands.”

The accusations have sparked an angry reaction from Chinese internet users, who have accused other nations of jealousy.

Chinese swimming team leader Xu Qi told China’s state-run Xinhua news agency that Ye Shiwen’s result had been expected.

“To compare Ye’s result with Lochte’s is meaningless,” he said.

“Ye was behind after 300m and she needed to try her best to win the race, but Lochte had already established the lead before the freestyle and didn’t need to do his upmost.”

Arne Ljungqvist, medical commission chairman for the International Olympic Committee, called the speculation sad.

“To raise suspicion immediately when you see an extraordinary performance – to me it is against the fascination of sport,” he said.

All medal winners at the Olympics are drug tested. In addition, any athlete whose performance is far better than anything they have achieved before can be targeted for extra tests.

China’s anti-doping chief has said that Chinese athletes have undergone nearly 100 drugs tests since arriving in London, and that not a single Chinese athlete had tested positive.

Who is Ye Shiwen?

• Born in 1996 in eastern city of Hangzhou

• Started swimming in 2003, reportedly after her teacher noticed she had large hands

• Joined the national team in 2008

• Won the 200m and 400m individual medley at the 2010 Asian Games