The Sumatran elephant could be extinct in the wild within three decades unless immediate steps are taken to slow the breakneck pace of deforestation, environmentalists warned today.

The International Union for Conservation of Nature recently listed the animals as "critically endangered" after their numbers dropped to between 2,400 and 2,800 from an estimated 5,000 in 1985.

The decline is largely due to destruction of their habitat, with forests all across the Indonesian island of Sumatra being clear-cut for timber, palm oil and pulp and paper plantations.

Sumatra has some of the most significant populations of Asian elephants outside of India and Sri Lanka and is also home to tigers, orang-utans and rhinos.

"The Sumatran elephant joins a growing list of Indonesian species that are critically endangered," Carlos Drews, of the conservation group WWF, said in a statement.

"Unless urgent and effective conservation action is taken, these magnificent animals are likely to go extinct within our lifetime."

Indonesia's endangered elephants sometimes venture into populated areas, searching for food, and destroy crops or attack humans, making them unpopular with villagers.

Some are shot or poisoned with cyanide-laced fruit, while others are killed by poachers for their ivory.