Cancer-stricken Olivia Newton-John is reported to have only weeks to live as she struggles to overcome her third bout of the disease.

Newton-John was diagnosed with breast cancer in June 2017. She also has a tumour in the base of her spine. It is the Grease star’s third cancer in her lifetime, but she has managed to successfully overcome it twice.

News site Now to Love reports people close to the 70-year-old say she is struggling to fight off her latest cancer and her prognosis is now “weeks, not months”.

News site radaronline.com reports Newton-John is determined to survive long enough to see her only child Chloe Lattanzi marry her partner James Driskill.

It is believed the couple have brought forward their wedding day amid Newton-John’s diagnosis.

"Olivia's bodily functions appear to be shutting down, but she refuses to let go until she makes it through Chloe's wedding day," a source told the website.

The star is currently living on a ranch in California with her husband John Easterling, where she is reportedly planning to spend her final days.

In September, Newton-John appeared relaxed as she told Sunrise presenters David Koch and Samantha Armytage of her health issues.

“I’m treating it naturally and doing really well,” the Grease star said.

Newton-John said she preferred not to refer to her cancer as a “battle” and was determined to overcome the deadly disease a third time.

“I like to say ‘win over’ because battle sets up this inflammation and anger that you don’t want, so I’m going to win over it again,” she said.

In December 2017, six months after her latest cancer diagnosis, she told Sunrise she had been able to continue touring despite her illness and was remaining positive.

“I have no pain and life is wonderful,” she said.

Newton-John has previously campaigned for more Government funding towards research into breast and brain cancers.