“She has passed away,” a family representative said to the newspaper.
The late actress, a mum of two was 76, and is survived by her children Duncan and Amelia.
She made her film debut in the 1966 picture Don’t Let It Get You. More recently though, Duncan made appearances in TV shows like A Country Practice, The Flying Doctors, All Saints, Water Rats, Always Greener and Winners and Losers.
A number of entertainment industry folks have taken to Twitter to pay tribute to the late star.
"So sad to hear of the lovely Carmen Duncan passing. She indeed was a beautiful soul. RIP," David Campbell wrote.
Publicist Ian Phipps wrote: "Vale to my darling friend Carmen Duncan, a wonderful and beautiful human being inside and out. Much love to Amelia, Duncan and family.
Sending love to her family during this difficult time.