Nine reported in a late news bulletin that the 27-year-old Dajka was dead but did not give details.
South Australia state police confirmed the body of a 27-year-old man was found inside a house belonging to Dajka, but did not confirm the identity.
No cause of death was released, but police said there were no suspicious circumstances.
Cycling Australia did not immediately respond to calls.
In 2002, Dajka won a Commonwealth Games gold medal in the team sprint and won the keirin at the world championships.
His career was derailed in 2004 when he was excluded from Australia's team for the Athens Olympics for lying to an inquiry into doping allegations at the Australian Institute of Sport.
He was among five former world champions under investigation after track squad member Mark French received a two-year ban from all competition and a lifetime ban from the Olympics for doping offenses. Dajka was not found guilty of any doping offence.
In 2005, Dajka was given a suspended three-month jail term for assaulting Australia's head track cycling coach Martin Barras.
He was subsequently barred from professional cycling for three years but successfully applied to be readmitted to competition after 12 months.
Dajka spent time in hospital with stress-related problems following his altercation with Barras and told local media he experienced problems with depression and alcohol.
