Michael Jackson claimed he had been given injections at 13 to delay puberty and keep his voice high.

Writing in his new book, 'This Is It', Murray - who met Michael three years before his death - revealed: "He began talking vaguely, seeming to have more difficulty describing precisely what happened to him. Maybe he was almost at the limit to his cathartic confession that night. But what Michael said left me the impression that he had been given injections, probably hormones, to delay puberty.

"After he had revealed for the first time to someone else his deepest held secret, Michael stopped talking." And Murray believes the shocking treatment accounted for his patient's bizarre character traits. In the extract, which has been published by the Daily Mirror newspaper, he wrote: "I often saw Jackson at his most exposed and confessional. He only agreed to share after making me swear, 'You will never breathe a word. Never.'

"I agreed. I was shocked when Jackson told me. It would explain all of Michael's unusual behaviour as well as his ¬morphological changes."

Despite being renowned for his dancing skills, Murray revealed the 'Billie Jean' singer was in constant pain because of an "advanced chronic fungal infection" and a number of callouses.

Despite being in pain for years, Michael's desire for privacy had meant he had refused to let a doctor check out his problems.

Murray said: "[They] were covered in callouses... and had an advanced chronic fungal infection. It turned out he always wore socks because he was so ashamed of the way his feet looked.

"I suggested he needed a podiatrist. A day after his feet were treated, he was amazed he could walk and dance without pain. Later I prescribed anti-fungal medications to clear the infection. It was a complete success. Meanwhile, I personally administered regular lotions and massages to remove the rough skin. "The fact Michael's feet, something critical to him, were in such poor condition was a sign not only had he neglected himself but those around him were not keeping a close eye on his wellbeing."