The disgraced entertainer, 92, reportedly requires carers to monitor him at his home as he is no longer able to eat.
While private investigator and author William Merritt added: “[He’s] battling a cancer of the neck, and gargles when he talks. It’s difficult to understand him, but he is still the entertainer.
“As soon as one of two people walk into the room, he turns into a big kid again. He’s an artistic type, and he’ll try to perform on cue, even when he’s unwell.”
In 2019, it was reported that Harris’ health had “declined rapidly”, with him only going out of the house with his carer.
The former TV presenter’s health is also said to have been gravely impacted following the death of his poodle earlier this year, according to MailOnline.
Harris, who lives in Berkshire with wife Alwen Hughes, who has Alzheimer’s disease, was released from prison in 2017 after serving three years of his five years and nine month sentence where he was found guilty of 12 counts of sexual assault, one of which was later overturned.
He was also reported to have been hospitalised during his time in prison after his diabetes spiralled out of control.
Harris has not spoken publicly since his release from jail but shared a statement in Merritt’s recent book, Rolf Harris: The Defence Team’s Special Investigator Reveals the Truth Behind the Trials.
He said: “I understand we live in the post truth era and know few will want to know what really happened during the three criminal trials I faced – it’s easier to condemn me and liken me to people like [Jimmy] Saville and [Gary] Glitter.
“I was convicted of offences I did not commit in my first trial. That is not just my view but the view of the Court of Appeal who overturned one of my convictions. I had already served the prison sentence by the time of the appeal.
“I changed my legal team after the first trial, and I was told that if the truth was out there, William [Merritt] would find it and he did. The evidence he found proved my innocence to two subsequent juries.
“I’d be in prison serving a sentence for crimes I did not commit if it were not for William’s investigation. It is difficult to put into words the injustice that I feel.”