A public prosecutor has appealed a court's decision to allow South America's Live Earth concert to go ahead as planned, arguing that police can not guarantee the safety of the 700,000 people expected to attend the open-air show on Rio's famed Copacabana beach.

A Live Earth representative vowed it would go on as scheduled.

The appeal by prosecutor Denise Tarin was her second try at canceling the show. On Thursday, Judge Maria Galhardo reversed her ruling to scratch the show after organizers convinced her there would be adequate security at the event.

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The show was canceled earlier this week after Galhardo agreed with Tarin, who argued that police would not be able to provide concert security because they are stretched thin with the upcoming Pan American Games and a huge crackdown on slum-based gangs.

Organizers appealed to Galhardo after authorities reversed course and said police were now available because an open-air gospel-music show scheduled for the same time was switched to a site where fewer officers will be needed.

Under Brazil's multilayered court system, judges' decisions can be repeatedly reversed, often within hours.

Organizers of the event — which is scheduled to feature Lenny Kravitz, Macy Gray, Pharrell Williams and Jorge Ben Jor — said they had not heard about the new appeal Friday and guaranteed the show would go on as planned.

"It's going to happen no matter what," Live Earth press spokeswoman Vanessa Vascouto said Friday night by telephone from Sao Paulo. "By tomorrow, there's no way to stop it."

Workers have set up a stage on Copacabana beach, where the Rolling Stones last year attracted a crowd of 1 million people. Tarin also imposed restrictions on that concert, arguing that the setting is not appropriate for huge concerts because it's difficult for police to craft "the slightest viable security plan."

The concert went off without major snarls or drawbacks.

Promoted by former U.S. Vice President Al Gore, Live Earth concerts are also scheduled for London; Tokyo; Johannesburg, South Africa; Shanghai, China; Sydney, Australia; Hamburg, Germany; Washington, D.C. and East Rutherford, New Jersey. A band of scientists also will perform in Antarctica, which, if the concert goes on in Rio, means there will be Live Earth music on all seven continents.

The Rio event is the only free concert for Live Earth, founded by Kevin Wall, an Emmy-winning concert producer. Proceeds from the other concerts will go toward the Alliance for Climate Protection, a nonprofit organization chaired by Gore.

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