With further rain looming, more families have abandoned their homes in Paraguay, the country hardest hit by the worst flooding in decades in the area bordering Uruguay and Argentina.
The floods have already forced more than 100,000 people to evacuate.
The weather phenomenon El Nino has exacerbated summer rains, swelling rivers in the region. The River Paraguay, which flows by the country's capital, Asuncion, has already reached 7.82 metres, its highest level since 1992.
Around 90,000 people have already left their homes in Asuncion. In Alberdi, about 120km further south, authorities have called for 7000 more people to evacuate because of cracks detected in the town's levee.
"We are very uncertain about what could happen with the (flood) wall and we do not want to run any type of risk, so the population has been alerted," said Paraguay's minister of national emergencies, Joaqun Roa. He said, however, that many people did not want to leave their homes for fear of looting.
This year's El Nino, which causes global climate extremes, is the worst in more than 15 years, the United Nations weather agency said last month. While it has worsened floods in some parts of South America, in others such as Colombia it has brought drought.
The Paraguayan government has declared a state of emergency in Asuncion and seven regions of the country to free up funds to help those affected. There is no official death toll yet.
Local media reported two people were electrocuted in their flooded homes and several were killed by trees falling in the storms that caused the flooding.
In northern Argentina, across Paraguay's southern border, some 20,000 people have had to evacuate in what local authorities have called the worst flooding in 50 years.
"Fortunately, the rains have lessened, and the rivers have stopped rising," said newly elected President Mauricio Macri, who suspended his Christmas vacation to visit the worst affected areas in Entre Ros province.
Macri, who studied to be a civil engineer, blamed the floods partly on climate change, and promised federal aid to help build housing further away from river shores and to raise flood defence walls in the area.
Next year, his government plans to focus on finding long-term solutions to the flooding problem, building new infrastructure that was long overdue, he said.
In Uruguay, the number of evacuees was 11,300, Fernando Traversa, the head of the national Emergencies Office said on Sunday. He said the situation was improving.
"Various rivers are already stabilising," he said.
In southern Brazil, flooding has forced 1800 families to leave their homes.
