According to Digital Spy, he wrote: "I have today announced the cancellation of the shows in Australia which breaks my heart. By way of explanation all I can say at this time is that since last year's illness I have tried in vain to work my way through the trauma that the doctors who saved my life warned me I would experience.
"They recommended complete rest and the type of post traumatic counselling which is available in cases like mine but I'm afraid I believed (wrongly) that making music and getting out there to perform for the audiences that bring me such joy would be therapy enough in itself.
"Unfortunately I seriously underestimated how difficult this year would be and although I was right to believe that the shows would bring me great happiness and that my voice would recover completely (I truly think that some of my recent performances have been my best ever) I was wrong to think I could work my way through the major anxiety that has plagued me since I left Austria last December."
He added: "All that's left for me to do is apologise to my wonderful Australian fan base and to promise faithfully that as soon as I completed these shows here in the UK I will receive the treatment which is so long overdue."
The singer had planned to open the newly-built Perth Arena on November 10, before playing playing in Adelaide, Sydney, Melbourne, Brisbane and Hunter Valley. Those who have bought a ticket will be given a refund.
Michael recently said: "What I have learned from coming so close to death, is that it makes no sense to plan for the future in detail. You never know what lurks around the corner."