Rio de Janeiro - Twenty-four people were killed by landslides spawned by heavy rains in a mountainous area of the Brazilian state of Rio de Janeiro, authorities said on Tuesday.

Another 18 people have been injured and 1 466 were forced to leave their homes or were left homeless following the heavy downpour that began late Sunday in and around Petropolis, 68km north of Rio de Janeiro, officials said.

The bodies of two boys and one girl who had been unaccounted for were found on Tuesday in a stream, firefighters said.

Earlier, a local official said two rescue workers were among the dead.

Nearly 250 soldiers and Civil Defence officials have been mobilised to assist residents of the area where 21 districts are either under water or hit by landslides, according to an official statement.

Up to 390mm of rain fell in some Petropolis districts in the space of 24 hours, when only 270mm was anticipated for the whole of March.

Rio state governor Sergio Cabral called on residents to leave high-risk areas and to seek refuge in shelters provided by city authorities as the heavy rain continued.

Petropolis Mayor Rubens Bomtempo urged residents to stay indoors and warned of the possibility of more landslides.

Brazilian President Dilma Rousseff, who attended Tuesday's installment of Pope Francis in Rome, offered Cabral federal help to deal with the impact of the deluge.

A civil defence statement said the heavy rain also affected other Rio state towns, including Angra dos Reis, Mangaratiba, Niteroi and Teresopolis.

In January 2011, more than 900 people died in Rio state's rugged region after heavy rain spawned flooding and landslides. - Sapa-AFP