At least 2000 penguins have died on the eastern coast of Uruguay in the last 10 days.
The reports said the cause of the penguin death however, remains a mystery.
The reports said Magellanic penguins, were found dead in the Atlantic Ocean and were carried by currents to Uruguayan shores.
"This is mortality in the water. Ninety percent are young specimens that arrive without fat reserves and with empty stomachs," the report published in NDTV quoted an expert having said.
The report also said that all samples taken have tested negative for avian influenza.
Magellanic penguins nest in southern Argentina. In the southern hemisphere winter, they migrate north in search of food and warmer waters, even reaching the coast of the Brazilian state of Espirito Santo.
The experts believe it is normal for some percentage of penguins to die, but this number is high.
There has been a similar incident last year in Brazil, when penguins were found dead for undetermined reasons.
The AFP report quoting Hector Caymaris, director of the Laguna de Rocha protected area, said that he counted more than 500 dead penguins along six miles (10 kilometers) of Atlantic coast.
Environmental advocates attribute the increase in Magellanic penguin deaths to overfishing and illegal fishing.
"From the 1990s and 2000s we began to see animals with a lack of food. The resource is overexploited," Richard Tesore, of the NGO SOS Marine Wildlife Rescue, was quoted by AFP as having said.
He also said a subtropical cyclone in the Atlantic, which hit southeastern Brazil in mid-July, probably caused the weakest animals to die from the inclement weather, mentioned the report.
In addition to penguins, Tesore was also saying that he has recently
