Sir Elton John has branded late pop star Michael Jackson 'mentally ill' and 'disturbing to be around' in his new memoir, Me, which is coming out on Tuesday, October 15, 2019. 

The British singer Elton, 72, writes ... "I’d known Michael since he was 13 or 14 ... He was just the most adorable kid you could imagine. But at some point in the intervening years, he started sequestering himself away from the world, and away from reality the way Elvis Presley did."

Elton John calls Michael Jackson

He goes on to say, "God knows what was going on in his head, and God knows what prescription drugs he was being pumped full of, but every time I saw him in his later years I came away thinking the poor guy had totally lost his marbles."

The singer also dropped a big allegation, writing ... "I don’t mean that in the light-hearted way. He was genuinely mentally ill, a disturbing person to be around."

Recalling a time he invited Michael to one of his parties, Elton claims the star wandered off and was found playing with his housekeeper's son.

He says: 'For whatever reason, he couldn’t seem to cope with adult company at all.'

Michael Jackson died suddenly of an overdose of sedatives administered by his personal physician, Conard Murray, in 2009.

He was later dragged into the news with claims of sexual abuse by Wade Robson and James Safechuck, which were detailed in HBO's "Leaving Neverland."