Sao Paulo (Brazil), May 5: A boat ferrying at least 80 people home from a party sank in Brazil's Amazon region, killing at least 15 and leaving dozens missing, according to rescue officials and Brazil's government.

The wooden Comandante Sales ferryboat capsized yesterday in a pre-dawn rainstorm on the Solimoes River, one of the Amazon's largest tributaries, said Fire Lt Col Raimundo Rodrigues da Silva.

It was unclear how many passengers the Comandante Sales was authorised to carry, but authorities said the ferry had been grounded several months ago after failing an inspection. Boats serve as buses in the area because there are few roads.

Rescue workers had recovered the bodies of 15 people by last evening when the search was called off for the night, according to Agencia Brasil, the government's official news agency. Most of those who died were women and several dozen other people were unaccounted for, Silva said.

The search was scheduled to resume today, and an investigation into the cause of the accident is expected to take at least three months. Navy Lt Raimundo Lenilton de Araujo told Agencia Brasil that torrential rains may have been a factor.

Amazon boats are frequently overloaded with passengers and cargo, which also may have been a factor, Silva said.

Revellers had rented the boat to travel from their small river town to another for a party, Brazilian media reported.