Olivia Newton-John star of Grease and multi-platinum selling singer, has died aged 73, her family says.

In a short statement her husband John Easterling said she had passed away at her California ranch on Monday morning.

"Olivia has been a symbol of triumphs and hope for over 30 years sharing her journey with breast cancer," the statement said.

"We ask that everyone please respect the family's privacy during this very difficult time."

Actress and singer Newton-John achieved commercial success as a country singer and sold millions of records.

But it was her role as Sandy in the film adaptation of Grease that catapulted her to world-wide fame.

Photo: AFP

After being diagnosed with breast cancer in the early 1990s, Newton-John became a leading advocate for cancer research.

Her efforts in the field were recognised by Queen Elizabeth, who honoured her with a Dame in 2020 New Year's Honours list.

John Travolta who starred opposite Newton-John in Grease, wrote on Instagram that she "made all of our lives so much better".

"Your impact was incredible. I love you so much," he wrote.

"We will see you down the road and we will all be together again. Yours from the first moment I saw you and forever!"