LONDON — It was to be the comeback of the young century: Michael Jackson using the "This is It" tour to retake his throne as King of Pop, lord of the dance and darling of the masses.

What grander stage than London for this late career magic? Jackson's much-hyped revival was to be a marathon, 50-gig tour that gave him a shot at redemption — not to mention repairing his tarnished image, lifting him out of debt and making millions for promoters.

Eager fans spent more than $90 million on tickets despite widespread doubts about the pop icon's stamina.

Now the star is dead — and one of the city's biggest arenas has 50 open nights. London, the city that was to be Jackson's launch pad back to glory, has become a symbol of the wreckage of his life.

The calamity has left Los Angeles-based tour promoters AEG Live, which operates the 02 Arena where Jackson was to have performed, with a huge problem. In addition to the money taken in by ticket sales, which must be refunded, the company had already paid Jackson millions and spent millions more getting ready for the July 13 premiere.

There is no question it's a disaster, said Chris Cooke, editor of the British music business bulletin CMU Daily. But no one knows the full magnitude.

"The question is how much they were insured, but they've been very quiet about that," he said. "Will the insurance company take the hit, or will they?"

He said AEG Live had been planning a world tour after the London gigs, and possibly an extended residency for Jackson at a Las Vegas hotel to capitalize on his revival after more than a decade away from the concert stage.

The goal was to give Jackson a total career makeover. Instead, the pressure to produce — and in effect, to compete with his younger self — may have contributed to his demise.

AEG Live said it would advise ticket holders early this week on how to get refunds, adding that fans should hold on to their ticket vouchers and proofs of purchase.

"At this moment our thoughts are with Michael's children, family and friends. We will announce ticketing information in due course," read a message on a huge screen outside the 02 Arena.

According to Bermuda-based insurer Validus Holdings Ltd., a group of insurers were covering the concert series through the Lloyd's insurance market, including its subsidiary Talbot Holdings. But Validus said it had less than $3 million at risk.

The refund process could be complicated by tickets being sold to people from a number of countries and because of the sheer volume of tickets sold, Werde said. Some 750,000 tickets, priced between $82 and $124, were sold, though some went for hundreds of dollars on Internet auction sites.