A Chinese official has blasted what he says are “biased” doping allegations against one of his country's young swimming stars who shattered a world record at London's Olympic games.

Beijing's anti-doping chief Jiang Zhixue told the Xinhua news agency that it is unfair to criticize Chinese athletes because of their success, which he says is the result of training and hard work.

His comments come after U.S. swimming coach John Leonard called the performance of 16-year-old Chinese swimming sensation Ye Shiwen “unbelievable” and suggested it may have been fueled by performance enhancing drugs.

Ye won gold in the women's 400-meter individual medley Saturday with an unprecedented performance, shattering the previous world record by over a second. She swam the final 50-meter lap faster than American Ryan Lochte did in the men's race.

Chinese swimmers have in the past been tainted with high-profile doping scandals, most notably in the 1994 and 1998 world championships.

Ye, who has denied taking performance enhancing drugs, races Tuesday in the final of the 200-meter individual medley.