Published Sunday, 18 May 2014
The former Beatles star was struck down with the mystery illness on Friday, prompting him to pull out of the first show of his Japanese mini-tour on Saturday.
He had hoped to be well enough to return to the stage on Sunday and make it up to fans of the Saturday gig by adding a new date for Monday, but both performances had to be axed completely as he remained unwell.
Reaching out to devotees online on Sunday, McCartney wrote: "Unfortunately my condition has not improved overnight. I was really hoping that I'd be feeling better today. I'm so disappointed and sorry to be letting my fans down."
The rocker's representatives are hoping to stage the shows at a later date and have advised fans to hold on to their tickets.
However, the 71-year-old remains positive he will bounce back from the ailment in time for Wednesday, when he is due to perform at the Nippon Budokan hall in Tokyo - 48 years after the Fab Four graced the same stage there in 1966.