Brazil's President Dilma Rousseff declared on Saturday a three-day national mourning to pay homage to the "victims of the storms that devastated several towns in Brazil, mainly in the mountainous region of Rio de Janeiro".

In a statement, President Rousseff also announced the immediate release of 100 million reais (about 60 million U.S. dollars) to help the victims in the flood areas.

The Brazilian government has already approved the release of 780 million reais (about 460 million dollars) to help the flood-hit cities in Rio de Janeiro's mountainous region.

Besides the cities in Rio de Janeiro, heavy rains also caused damage and destruction in some cities in Sao Paulo and Minas Gerais in the southeast region.

According to the Civil Defense's latest bulletin, the flood and mudslides also left at least 6,050 people homeless and another 7,780 people living in risky areas had to abandon their houses temporarily and take refuge in gymnasiums and public schools.

Rio de Janeiro's governor Sergio Cabral announced on Saturday seven days of mourning in honor of the victims starting from Monday.

The death toll in the storms which devastated part of Rio de Janeiro state last week has reached 600, the authorities confirmed.

The rainstorms are the worst natural disaster in Brazil's history, surpassing a flood in 1967 in Caraguatatuba, Sao Paulo state, which killed 436 people.

However, as many neighborhoods remain inaccessible due to mudslides, the death toll is likely to be much higher, authorities said.