Olivia Newton-John has responded to the recent rumours about her health, telling fans she is "doing great".

The Australian actress, best-known for starring alongside John Travolta in the 1978 film Grease, revealed in September she had been diagnosed with cancer for the third time in three decades.

Recent media reports out of the US claimed Newton-John was so unwell that she only had "weeks" to live.But the 70-year-old star on Thursday moved to assure fans that the reports are false.

In a video released on Twitter, she said: "Happy New Year everyone, this is Olivia Newton-John and I just want to say that the rumours of my death have been greatly exaggerated, to quote a very famous quote."

"And I am doing great and want to wish all of you the happiest, healthiest 2019 as possible and thank you all for your wonderful love and support for me and for my Olivia Newton-John cancer wellness centre in Melbourne, Australia," she said smiling.

"Thank you so much, Happy New Year."

In September 2018, Newton-John revealed doctors had found a tumour in her lower back in 2017, 25 years after she was first diagnosed with breast cancer.

Forced to cancel numerous tour dates for treatment, the singer said she was treating the illness "naturally" and was using cannabis oil made from marijuana her husband grows in California to alleviate the pain.

This week friends and family of Newton-John rubbished the rumours she had just "weeks" to live, after a Radar report was picked up by Australian news outlets on Wednesday.

The singer's niece, Tottie Goldsmith took to Instagram on Wednesday to deny the "distressing" claims.

"Just giving you the heads up that Livvy is in good health, so let’s leave that distressing rumor where it belongs," wrote Ms Goldsmith.