It's a Knockout host Fiona MacDonald announces her own death ...

Australian TV star Fiona MacDonald, best known for hosting It's a Knockout, has died aged 67.

MacDonald battled motor neurone disease for several years and she announced her own death in a heartbreaking social media post.

"My sister Kylie is posting this because I have left the building," MacDonald's posthumous message on Instagram read.

"Was very peaceful the boys and Kylie stayed with me to say goodbye. While I've never wanted to die, the thought of leaving my tortured body was a relief."

In her message, MacDonald said the "past few months have been tough" prior to her death.

She said she'd struggled to swallow food and her feeding tube had not worked.

"It went straight in and straight out," she continued.

"I have been slowly starving, growing weaker and weaker. I've also developed terrible back pain because my muscles aren't supporting my frame."

The former TV host also said her signature "black humour" had helped during the toughest moments.

She had decided to stop medical intervention shortly before her death and went into hospital for palliative care.

"So let's not call it goodbye as I hope to see you again on the other side," MacDonald said.

"I carry your love and laughter with me and hope you'll remember mine."

As well as hosting the '80s version of the Aussie show It's A Knockout, MacDonald was also a founding member of the children's show Wombat.