Brady, 79, was a patient at Ashworth Hospital in Merseyside where he was being force-fed in hospital.
But his condition deteriorated to the point he was being cared for by staff who help terminal cancer patients, it was claimed.
A source told The Sun earlier today: “He is gravely ill and everyone there is prepared for him dying.”
Brady and Myra Hindley, who died in prison in 2002, tortured and murdered five children in the 1960s. Four of the victims were buried on Saddleworth Moor in the south Pennines.
Brady was jailed for three murders in 1966 and has been at Ashworth since 1985. He and Hindley later confessed to another two murders.
In 2013 he asked to be moved to a Scottish prison so he cannot be force-fed - as he can in hospital - and where he could be allowed to die if he wishes.
His request was rejected after Ashworth medical experts said he had chronic mental illness and needed continued care in hospital.
In February he was refused permission to launch a High Court fight to have the lawyer of his choice representing him at a tribunal where the decision would be reviewed.
Brady has also been urged to “do the right thing” and reveal where the last of his child victims is buried.
Terry Kilbride, whose brother John, 12, was also murdered by Brady, begged him to tell police where he dumped the body of Keith Bennett, who went missing aged 12 in 1964.
He told The Sun: “I would beg him to do the right thing on his deathbed and tell us where Keith is. Now is the time for him to stop playing tricks and come clean.
“If he takes it to the grave, I will feel so sorry for Keith’s family. There will only ever be another search if there’s fresh evidence. That has to come from him.”
The serial killer, 79, who now uses the name Ian Stewart-Brady, is a patient at Ashworth Hospital on Merseyside where he is reportedly receiving palliative care.
At a court hearing in February lawyers said he had been bedridden for the last couple of years and it was “fair to say” he is terminally ill, with emphysema among his ailments.
Mr Kilbride has said he hopes the killer “rots in hell”.
“We’ll certainly celebrate his death when it comes. Good riddance,” he said.