The World Wildlife Fund said it has evidence that the rare Sumatran rhinoceros is breeding on Borneo island.
Raymond Alfred, an official with the WWF, said film taken in February in a remote forest in Malaysia's Sabah state indicated that a rhinoceros was pregnant.
Mr Alfred said today the area must be protected from logging activity.
The picture is only the third piece of evidence since 2007 suggesting that the critically endangered species might be breeding in the wild.
Conservationists warned the rare animals could face extinction in the next 10 years.