Reports of the number of people on the Comandante Sales passenger boat vary from 80 to 150, far more than the allowed capacity of 50.

Fire-fighters and 15 divers are trying to locate survivors in the silty river.

The accident occurred on the Solimoes at around dawn on Sunday about 80km (50 miles) from Manaus, the city's fire department said.

Boats on the Amazon and its tributaries are frequently overloaded in passengers and cargo.

Fire Lt Col Raimundo Rodrigues da Silva said the dead had not yet been identified.