The last song recorded by Olivia Newton-John has been released posthumously online, a week before she is honoured with a state funeral.

Newton-John died at her ranch in southern California in August last year aged 73.

The song is a duet of Dolly Parton’s country hit Jolene, which she sang alongside Parton in an intimate studio recording session before her death.

A music video released on YouTube on Saturday shows the pair clearly thrilled to be recording their vocals together.

 “I am excited, I have always wanted to sing with Dolly,” Newton-John says in the video.

She famously covered the song in 1976, three years after the song was originally released by Parton.

A heart-wrenching music video of the last song Olivia Newton-John ever recorded has been released online – with a surprising duet partner. Photo / YouTube

“I am so excited to be working with Olivia Newton-John, one of my favourites of all time,” Parton said in the video.

“We’ve always stayed close through the years and I’m so proud to be a part of this duet project.”

• Elton John, Olivia Newton-John honoured in UK New Year's Honours List
• James Irwin: Rest in peace Olivia Newton-John, you absolute legend

A state memorial service is being held to honour the life of Newton-John at Hamer Hall Arts Centre in Melbourne on Sunday, February 26.

Newton-John emigrated from England with her family when she was 5 and spent most of her childhood in Melbourne.

The beloved actor and singer skyrocketed to international fame when she appeared alongside John Travolta in the 1978 musical film Grease.

She established herself as one of the best-selling music artists of all time and was nominated for 12 Grammy Awards including four wins.