Australian Singer Helen Reddy Dies in Los Angeles, Aged 78

Singer Helen Reddy attends the opening night of "The Death And Life of John Lennon" at the Parade Theatre on March 8, 2006 in Sydney, Australia. (Patrick Riviere/Getty Images)

Australian singer, actor and activist Helen Reddy has died, aged 78.

"It is with deep sadness that we announce the passing of our beloved mother," her children Traci and Jordan posted on Facebook.

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

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

She had been diagnosed with dementia in 2015.

Hundreds of Reddy's fans from around the world have begun flooding her official fan page on the Facebook platform, praising her achievements and mourning her passing.

"Quiet Please, There is a Lady Leaving the Stage," the page administrator posted.

Reddy was born on October 25, 1941, in Melbourne, Victoria.

Sydney