Some towns remain isolated and hopes of finding the more than 130 people who are still missing are dwindling.

Further heavy rains forecast for this week are expected to further exacerbate the situation in the region.

Many residents had to leave their homes, with some of the most vulnerable people evacuated by rescue workers.

The Brazilian Airlines Association said on Tuesday that the airport in Porto Alegre would remain closed until at least the end of the month after the Guaíba river burst its banks and flooded the runway and key buildings.

The river reached a record high level of 5.3m (17.4ft), local officials said. The previous record was reached in 1941 and stood at 4.76m.

The airport is not the only large building which had to close in Porto Alegre, a city which is home to some 1.5 million people.

The pitch of the Arena do Gremio stadium is also covered in brown sludge.

The situation in some of the areas surrounding the city of Porto Alegre is even worse. Canoas is one of those badly hit.

The extreme weather has been caused by a rare combination of hotter than average temperatures, high humidity and strong winds.

Climate expert Francisco Eliseu Aquino told AFP news agency that Rio Grande do Sul had always been a meeting point between tropical and polar air masses but said that "these interactions intensified with climate change".