The antigen tests on 30 of the red-haired creatures in Sabah were conducted last Tuesday and all came back negative, wildlife officials said.

They were the first virus tests on orangutans in the country and were ordered after staff at a rehabilitation centre and wildlife park became infected.

“Testing for Covid-19 has been a vital tool in helping us get through this pandemic, and it is similarly important for this orangutan population,” said Sen Nathan, assistant director of the Sabah Wildlife Department.

“The disease could prove vastly detrimental to their health and set back their rehabilitation.”

Vets will continue to closely monitor the apes and tests will be conducted regularly, officials said.

Animals have become infected with Covid-19 on occasion. Over the weekend, a zoo in Atlanta announced that several of its gorillas had tested positive. Domestic cats, dogs and at least one ferret have also been infected.

Bornean orangutans are classified as “critically endangered” by protection group the International Union for Conservation of Nature.

Their populations have declined by more than 50% over the past 60 years, according to the WWF, as the animals’ forest habitat has been progressively cut down to make way for agricultural plantations.