MJ Memorial Only for Ticketholders

Ticketless fans have been warned to stay away from Michael Jackson's star-studded memorial service amid fears of riots.

Los Angeles police have urged people not to head to the Staples Center in the city's downtown area for tomorrow's event unless they are guaranteed entry.

Authorities fear that up to one million fans will descend on the city.

More than 1.6 million people entered a lottery to get tickets, but only 17,500 were successful.

Some tickets were being offered for sale on eBay for as much as $20,000.

British Airways said it had a "huge influx" of reservations over the past few days from  people hoping to make their way to the event from the UK. Local police have been building barriers around the Staples Center, which can accommodate only 20,000.

"Anybody who does not hold proper credentials, tickets to get in to the event, will not be allowed inside the security zone," Los Angeles Police Department Assistant Chief Jim McDonnell said.

Among the celebrities expected to pay tribute to the so-called King of Pop at the event include Diana Ross, Stevie Wonder, Justin Timberlake, Mariah Carey and Jennifer Hudson.

Longtime MJ pal Elizabeth Taylor will reportedly read the eulogy, while other guests may include Whitney Houston, Beyoncé, Jay-Z, Lionel Richie, Liza Minnelli and Aretha Franklin.

Before the tribute, there will be a private ceremony for family at Forest Lawn cemetery.

This is definitely going to be a mob scene. We hope the police are well-prepared.

—Gavin Wilson, Splash News