Samples from the dead animals showed no trace of abnormalities or anthrax poisoning, ZimParks said in a statement.

However, an investigation found that the hippos had moved 10 kilometres (six miles) from their habitat in search of food, it said.

The "findings strongly indicate that the majority of mortality cases up to this point are directly linked to severe nutritional deficits rather than infectious diseases," the statement added.

Zimbabwe is among several southern African countries that have been hit hard by drought over the past months. Rain had only started falling in recent days, ZimParks said.

About half of the hippo population in the area, known as the mid-Zambezi region, was found to be in poor condition with pelvic bones and spines showing, which is a sign of malnutrition or lack of adequate food, it said.

strs/br/kjm