The BBC quoted the concert promoters as explaining the dates had been pushed back because Jackson needs more time to rehearse with the show's creative director Kenny Ortega, who had worked on two of Jackson's previous tours, as well as the "High School Musical" movies.
Jackson's July 8 gig has been rescheduled for July 13. Three other July dates, however, are now not expected to take place until March 2010.
"Kenny and Michael are, at the same time, both creative pioneers and perfectionists," AEG President Randy Phillips said in a statement. "This show has grown in size and scope, thereby necessitating more lead time for manufacture of the set, programming the content for the massive video elements, and, most importantly, more time for full production and dress rehearsals. ... As much as we agonized over this change in the original schedule, we are sure the fans will understand when they experience the level of entertainment Michael Jackson intends to deliver."
Jackson, who last toured 12 years ago, is scheduled to perform at the O2 for 50 nights.