Australians expressed shock and sadness on Tuesday as they woke up to the news that 1970s and '80s pop icon Olivia Newton-John, star of the hit movie musical "Grease", had died at age 73 at her home in Southern California.

From the Prime Minister on down, tributes flowed for the four-time Grammy winner, who grew up in Australia. She was hailed for her passionate work in promoting cancer research and wellness care after battling the disease for 30 years.

In Sydney, locals and tourists shared warm memories of growing up with the soundtrack of Newton-John, including songs such as "Physical" and "Hopelessly Devoted to You".

"I used to watch it (Grease) a lot when I was a kid and teenager, so yeah, it's a big shock. She's an Australian icon, so very upsetting, and way too young to die," Clara Zwack, a science research fellow, said in Sydney.

Requests poured in to Australian Broadcasting Corp to show Newton-John singing the 1980 hit title song from the movie Xanadu.

The pop star first battled breast cancer in 1992 and in 2017 disclosed a recurrence had spread to her lower back, forcing her to cancel performances.

Her death followed the loss of two other Australian musical figures in just over a week - Judith Durham, lead singer of The Seekers, and Indigenous singer and songwriter Archie Roach.

"She's done so much for Australia with ... the wellness clinics down in Melbourne, so, yeah, real shock, sadness," said 69-year-old Sydney resident Lynette.

Prime Minister Anthony Albanese called Newton-John a "joyful glow in our lives".

"Her legacy will live on, in her music, her films and her determination that one day we will find a cure for cancer," Albanese said on Twitter.