McCullough died on Thursday in hospital on remote Norfolk Island, HarperCollins, The Hindu reported quoting a statement by Australia's  publishing director Shona Martyn.

McCullough had continued producing books despite a string of health and eyesight problems by using dictation, Ms. Martyn said.

“Ever quick-witted and direct, we looked forward to her visits from Norfolk Island and the arrival of each new manuscript delivered in hard copy in custom-made maroon manuscript boxes inscribed with her name,” Ms. Martyn said.

McCullough wrote 25 novels throughout her career. Her final book Bittersweet was released in 2013.

Before becoming an author, McCullough studied neuroscience and spent 10 years as a researcher at Yale Medical School in the United States. She established the neurophysiology department at Sydney’s Royal North Shore Hospital.

She is survived by her husband, Ric Robinson.