The government of Argentina has declared three days of national mourning after more than 50 people died in floods.

Days of torrential rains swamped Argentina's low-lying capital and province of Buenos Aires.

At least 46 died yesterday in and around the city of La Plata, Governor Daniel Scioli said.

That area saw some of the heaviest rain with almost 40cm falling in just a few hours.

Six deaths were reported a day earlier in the nation's capital Buenos Aires.

Many people climbed on to their roofs in the pouring rain after storm sewers backed up.

Water surged up through drains in their kitchen and bathroom floors, and then poured in over their windowsills.

President Cristina Fernández, who grew up near La Plata, visited the flood zone and promised to send more police to calm people's fears that evacuated homes could be looted.

She said: "People are fearful. It goes beyond the material loss.

"Several people in the neighbourhood told me ... that they are seeing some strangers in the area and they're fearful of public safety."

She announced security measures to combat vandalism and help for identifying the dead.

The rains also flooded the country's largest refinery, causing a fire that took hours to put out.

The La Plata refinery suspended operations as a result, and Argentina's YPF oil company said an emergency team was evaluating how to get it restarted.