Chinese swimmers underwent more than 2,500 drug tests last year and no positive results returned, the Chinese Swimming Association (CSA) said on Wednesday.

Of the 2,539 dope tests, 1,523 were carried out by the FINA and the World Anti-Doping Agency, and the rest conducted by the Chinese doping control authorities, according to the CSA.

"China's recent breakthrough in swimming are the results of scientific training and hard work," the CSA said in a statement.

The CSA statement came after Chinese swimmer Ye Shiwen was plagued with doping speculations after the 16-year-old won the women's 400m IM gold medal with world record-breaking performance on Saturday.

FINA also released a statement on Wednesday to defend Ye.

"Following the recent comments reported in the media, FINA would like to clearly state that there is no factual basis to support this kind of insinuations related to the performances of the Chinese swimmer, Shiwen Ye. This athlete has fulfilled all of the FINA Doping Control obligations, having been tested on four occasions in the last twelve months, including twice before the Chinese Olympic Trials in 2012," said FINA on its official web.