The operation came a day after hundreds of police occupied a slum in Sao Paulo, Brazil's largest city, following violence which erupted after police allegedly killed a drug suspect.

Police told AP that three officers were shot in the Sao Paulo violence and local residents reported at least two civilians were injured.

Rio experiences daily clashes between police and heavily armed drug gangs that control hundreds of slums in the city, making its streets some of the most dangerous in the world.

City police often say that those killed in their raids are suspected drug dealers and traffickers, but human rights groups have accused police of brutality, corruption and summary executions of suspects.

Last year a United Nations report said that local police kill an average of three people a day in Rio de Janeiro alone.