RIO DE JANEIRO, April 3 (Reuters) - Brazilian police backed by helicopters and armored cars killed at least 11 suspected drug gang members on Thursday in a raid on two Rio de Janeiro slums, a police official said.

About 150 police entered the slums in the west of the city in an attempt to arrest the suspected leader of a drug gang controlling the area, according to precinct police chief Rodrigo Oliveira.

"We came under fire after circling the communities," he said. "We believe the trafficker escaped."

Hundreds of slums perched on the picturesque city's hillsides have become battlegrounds between drug gangs and police, who rights groups have accused of military-style raids and summary executions that further alienate the city's poor.

Rio police killed 1,330 suspects last year, up 25 percent from 2006, according to their own figures.

The violence is increasingly embarrassing for the government at a time when many Brazilians are feeling the benefits of strong economic growth and anti-poverty programs.

The latest killings happened less than a month after President Luiz Inacio Lula da Silva made a rare visit by a Brazilian leader to Rio's slums during which he launched a new infrastructure project and told police to treat residents with respect.

Television footage showed bodies strewn on the streets of the Coreia and Vila Alianca slums after Thursday morning's gun battle.

Police said they arrested at least seven suspects and confiscated two machine guns, a hand-grenade and three fake police uniforms as well as cocaine.

(Reporting by Rodrigo Viga Gaier; Writing by Stuart Grudgings; Editing by Angus MacSwan and Sandra Maler)

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