Michael Jackson [ tickets ] has added 18 more shows to his O2 Arena run in London later this year after overwhelming pre-sale traffic.

The King of Pop, who last week announced plans for 10 dates along with a claim that "this is it" for the English capital, is now set to perform a total of 28 gigs beginning July 8 and wrapping up September 10. Pre-sale tickets became available this morning (3/11) to those who successfully completed the registration process at MichaelJacksononLive.com, earning them a chance at the early offer. However, the volume of user traffic delayed transaction processing.

"We have witnessed an unprecedented level of demand for the Michael Jackson concerts at O2," Chris Edmonds, the managing director of Ticketmaster U.K., said in a prepared statement. (Ticketmaster is LiveDaily's parent company.) "Unfortunately due to a technical issue, we were unable to facilitate all immediate ticket requests. Apologies to those fans who were unable to log on, but fans should keep on trying to purchase tickets."

According to promoter AEG Live, 19 scheduled performances are now sold out of pre-sale tickets, which consist of roughly half of the total tickets available for each venue. The remaining tickets go on sale to the general public Friday (3/13).

Jackson's full performance schedule for the O2 run is posted at MichaelJacksononLive.com