Two hippos have tested positive for COVID-19 at the Antwerp Zoo in Belgium in what could be the first reported cases in the species, zoo staff said.

Hippos Imani, aged 14, and 41-year-old Hermien have no symptoms apart from a runny nose, but the zoo said the pair had been put into quarantine as a precaution.

"To my knowledge, this is the first time in this species. Worldwide, this virus has been reported mainly in great apes and felines," said the zoo's vet, Francis Vercammen.

The coronavirus is thought to have jumped from an animal to a human, and it is proved to have passed from humans to animals.

Pets including cats, dogs and ferrets have become infected following contact with their owners, while in zoos, cases have been reported in animals such as big cats, otters, primates and hyenas.

The disease has also spread in mink farms and to wild animals, such as deer.

Antwerp Zoo is investigating the causes of the contagion. None of the zookeepers had recently shown COVID-19 symptoms or tested positive for the virus, the zoo said.