Thousands of Michael Jackson fans have joined a pre-sale to try and secure tickets to the singer's comeback gigs at London's O2 Arena.

A select number of tickets went on sale at 7am (GMT) this morning for fans who had been sent a registration code by organisers.

All ticket outlets are experiencing high volumes of traffic, with Ticketmaster's website currently displaying a 15 minute wait time.

There are also reports that some fans have struggled to get onto O2's priority ticket website.

Demand for the shows, which begin on July 8th, has exceeded expectation, with over a million people registering for the chance to buy tickets.

Organisers are widely expected to announce details of additional dates.

In an email this morning, fans who had failed to secure a registration code were told to “monitor” their emails for a further announcement.

“We are seeking approval to add more shows so all of Michael's fans can be accommodated,” the email said.

Jackson, now 50, has not performed a full concert since he was cleared of child molestation charges in 2005. His last full tour, entitled HIStory, took place in 1996 and '97.

This singer told fans at the O2 Arena last week that he “loved them” - and insisted that the concerts in July would be his “final curtain call”.

In total, the singer is expected to earn upwards of $400m for his comeback, which also includes a 3D film deal.

(by Jason Gregory)