Singer Helen Reddy poses at the 2015 G'Day USA Los Angeles Gala.

Australian singer Helen Reddy, best known for her feminist anthem "I Am Woman", has died in Los Angeles aged 78, according to a statement from her children on Wednesday.

"It is with deep sadness that we announce the passing of our beloved mother, Helen Reddy, on the afternoon of September 29th 2020 in Los Angeles," the statement on her official Facebook fan page said.

The trailblazing musician from Melbourne shot to global stardom with the 1971 hit "I Am Woman", which became the rallying cry of the women's liberation movement.

Born on October 25, 1941, Reddy married three times and had two children, Traci Wald Donat and Jordan Sommers.

"She was a wonderful mother, grandmother and a truly formidable woman," they said.

 Reddy, the Australian-born singer who scored an enduring hit with her feminist anthem "I Am Woman.”

"Our hearts are broken. But we take comfort in the knowledge that her voice will live on forever."

Reddy, who lived in Los Angeles, was diagnosed with dementia in 2015.

She was born to show-business parents and began performing as a small child in Australia.

Reddy later moved to the United States where she recorded a string of hits in the 1970s, including "Angie Baby" and "Delta Dawn", topping the Billboard charts three times.

An Australian biopic detailing her rise to fame premiered at the Toronto International Film Festival in 2019.