Some 1, 500 police and commandos took part in the operation in the northern favelas of Jacarezinho and Manguinhos, which began at 05:00 (08:00 GMT).
BBC: Brazil drugs raids: Police surge into north Rio slums
2.
Moving in groups of eight, police made their way through the alleys of Jacarezinho, searching houses, while armoured cars took up position beside rubbish dumps, news agency AFP reported.
BBC: Brazil drugs raids: Police surge into north Rio slums