An animal conservation group has declared the black rhinoceros as extinct and warned that two other subspecies of the animal may also be lost forever due to poaching.

The International Union for Conservation of Nature (IUCN) struck out the name of the black rhino, a native of West Africa, from its Red List of Threatened Species. The last sighting of the animal was in 2006.

The IUCN said white rhinos of Central Africa and Javan rhinos of Vietnam may also be struck out from the list if no conservation efforts are taken. In a posting on its website, the IUCN also cited international organized crime groups targeting rhinos and increasing illegal demand for rhino horns and commercial poaching are the main threats faced by rhinos.

The group claims that Vietnamese poachers killed the last Javan rhino last year.

Simon Stuart, chair of the IUCN Species Survival Commission, said managing habitats in order to improve breeding performance must be strengthened now to prevent other rhinos from fading into extinction. Such measure has increased the wild population of the Southern White Rhino subspecies from 100 at the end of the 19th century to an estimated 20,000.

The IUCN's red list is the world's most comprehensive inventory of the global conservation status of biological species. It classifies species as extinct, extinct in the wild, critically endangered, vulnerable, near threatened, least concern, data deficient and not evaluated.

The current list has more than 61,000 species, including plants.

"The IUCN Red List is critical as an indicator of the health of biodiversity, in identifying conservation needs and informing necessary changes in policy and legislation to drive conservation forward," said Jean-Christophe Vié, Deputy Director of IUCN's Global Species Programme. "The world is full of marvelous species that are rapidly moving towards becoming things of myth and legend if conservation efforts are not more successfully implemented-if we do not act now, future generations may not know what a Chinese Water Fir or a Bizarre-nosed Chameleon look like."