China's anti-doping agency says it has recorded six recent positive drugs tests by Chinese swimmers.
The agency confirmed the cases on Thursday after the British newspaper The Times reported it had been approached by whistleblowers in Chinese swimming who claimed that five positive tests had been kept secret.
Zhao Jian, deputy director of the Chinese agency known as CHINADA, said it had recorded three positive tests, all for clenbuterol, in late August and early September.
The swimming federation will soon issue punishments in those cases and the results will be made known, he said.
Zhao said there have also been three positive tests since the beginning of 2016, all in January, but those remain under investigation and will be publicised within 20 days of punishments being issued in accordance with WADA regulations. He said the World Anti-Doping Agency has been kept informed about all positive tests.
Names of the swimmers have not been released.
The Times story said whistleblowers approached the paper to "avoid a storm" before China's Olympic trials next month and asked the paper to pass the information to WADA, which it said is now investigating.
"Since the very beginning, China has never covered up any positive doping tests," Zhao said.
"I am not sure what (the paper) really referred to and the report was vague. So there has not been such a sensational thing such as a cover-up and it is not true."
The Times also reported that coach Zhou Ming had been working with swimmers in Tianjin.
Zhou was banned by world governing body FINA in 1998 after overseeing the scandal at the world championships in Perth, Australia, when four swimmers tested positive and vials of human growth hormone were discovered in a swimmer's bag by Australian customs.
