7News claims there are fears the Australian could lose some of the use of his left arm.

Five-time Olympic gold medallist Ian Thorpe is reportedly in intensive care at a Sydney hospital with a serious infection.

7News has reported the 31-year-old contracted the infection following surgery near his home in Switzerland.

He apparently returned to Australia following the surgery and is now being treated in Sydney.

(Photo: AP/Bryan van der Beek)

Those close to Thorpe are quoted as claiming it’s feared the infection could permanently jeopardise the full use of his left arm.

In February it was revealed the 31-year-old had been battling depression.

The former swimmer was later admitted to rehab.

There has so far been no comment from his representatives.

(Photo: Jason Reed / Reuters)