Bahia Blanca in the country's east was lashed with double the annual rainfall for the area in a single day, March 7, causing $400 million of damage to the city of 350,000 people.

"With deep sorrow, we confirm that the chief prosecutor Juan Pablo Fernandez reported the discovery of the body of Pilar Hecker, one of the girls who went missing during the March 7 flooding," the mayor's office said in a statement.

Argentines were shaken by fate of Hecker and her one-year-old sister, who is still missing.

They were dragged 350 meters (1,150 feet) by a torrent of water when their mother moved them from her car to the truck of a man attempting to assist them.

The four climbed onto the roof of the van but a flood surge ripped away the driver and the girls.

The mother survived, as did the children's father, but the body of the van driver was subsequently located.

Buenos Aires had ordered three days of national mourning over Bahia Blanca's worst disaster in decades.