Rio de Janeiro police found two caimans in a raid on one of the city's slums, saying the crocodile-like reptiles were used by drug traffickers to intimidate their enemies and dispose of bodies.

Police were conducting a raid in the west of the Brazilian city looking for a drug gang boss when they came across the animals in the backyard of a house in the Coreia slum.

"The caimans are a symbol of power of the traffickers. When they catch a rival, they kill him and give him to the caimans," Ronaldo Oliveira, head of the robbery and car theft unit, was quoted as saying on O Globo newspaper's website.

Television footage showed police officers carefully placing the small reptiles in the back of a truck.

Rio's heavily armed drug gangs, with names like "Red Command" and "Friends of Friends," control many of the city's hundreds of slums and regularly battle over territory.

Some slums are next to the city's tropical forest areas, where gangs have been known to train and launch invasions of rivals' territories.