(Fixes spelling of band name in 11th paragraph)

By Andrei Khalip

RIO DE JANEIRO, July 4 (Reuters) - Brazilian organizers of the Rio de Janeiro leg of the Live Earth global concerts were trying to convince authorities on Wednesday not to cancel the Saturday show due to security concerns.

The Rio state prosecutor's office said earlier there were not enough police to safeguard the climate change awareness concert on Copacabana beach as all security efforts would be concentrated on preparations for the Pan American Games, starting July 13.

Police have stepped up operations against drug gangs in Rio's slums in the run-up to the Games. Last week, they raided a slum on the city outskirts, killing about 20 people after a long siege of the area in which two dozen people had been killed and more than 60 wounded since May.

On Wednesday, police and drug traffickers fought gun battles in two slums, including one by the busy Avenida Brasil thoroughfare. An officer and a bystander were wounded.

If late Tuesday's court injunction suspending the show is not overruled, it could spell a second cancellation in the Live Earth series. The injunction can still be appealed in a higher court, officials said.

Mondo Entretenimento, Live Earth's Brazilian promotion company, said in a statement it was "working to guarantee the realization of this important international event."

Its spokeswoman said the promoters were in meetings with Rio state prosecutors who had obtained the court injunction. Live Earth officials abroad did not have immediate comment.

The municipal RioTur tourism authority, which is involved in the event organization, said it and show producers had made all necessary arrangements to provide security at the event and were ready to meet any other official demands.

A giant beach stage in front of Rio's plush Copacabana Palace hotel has already been erected.

Organizers said they were planning to use dozens of observation towers and platforms as well as police cameras in the security scheme for the event.

Eight cities are due to hold the concerts on Saturday, aiming to raise awareness about global warming with performances by stars including Madonna, Shakira and the Beastie Boys.

Last month, Istanbul was dropped from the list cities set to hold the concerts because of a lack of interest and security concerns. Ticket sales have been slow for most Live Earth shows and organizers had to shift venues in Johannesburg in a bid to improve sales.

Performers including Lenny Kravitz, Pharrell Williams, Jorge Ben Jor and Macy Gray have been lined up to play on Copacabana to an expected audience of 1 million people in the only free, open-to-all event of the Live Earth series.

Rio will host 5,500 athletes from across North and South America as well as an estimated 800,000 tourists for the Pan American Games.

A cancellation would be embarassing for city officials who hope the events will showcase Rio's legendary charms instead of exposing its rampant crime.

Rio has one of the highest murder rates in the world, with a toll comparable to some war zones. At least 1,800 people were killed in the first four months of 2007 in the metropolitan area, official figures show.

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