The 24-year-old South African won the 200 metres butterfly title at London 2012 and also scooped silver in the 100m butterfly.

His Olympic title saw the Durban native beat the United States' Michael Phelps, the world's most decorated Olympian who has won 18 gold medals, into silver.

Preparations for Rio, however, have been hit with double anguish although he has vowed to continue training.

"The Rio Olympics are just a few weeks away but I can confirm that both my parents are fighting cancer," said Le Clos.

"My Mum Geraldine has breast cancer which has returned since her remission in 2010. 

"She has recently undergone a double mastectomy and is now having chemo. 

"My Dad Bert developed prostate cancer and has also undergone an operation in late June.

"It has not been an easy time but I am training hard for Rio. 

"More than anything else I want them to win their battles. 

"I also hope that they will be in Rio.

"I would ask my friends in the media to respect their recovery. 

"I will also not be doing any media prior to Rio."

Bert le Clos provided one of the moments of the London Games when he enthusiastically celebrated his son's gold medal winning performance.

An emotional interview on the BBC saw him proclaim Chad as "my beautiful boy" and won him fans all over the world.

Chad le Clos has also won six short course and three long course World Championship titles during his glittering career so far.

He is a quadruple Commonwealth Games champion and has topped the podium at the All-Africa Games on nine occasions.

In 2010, he won five medals at the Youth Olympic Games in Singapore, including gold in the 200m medley.