Three more endangered Borneo pygmy elephants were found dead Wednesday in Malaysia of suspected poisoning, wildlife officials said, adding to 10 carcasses discovered earlier this month.

They may have ingested poison spread by oil palm plantations to keep "pests" away, said Laurentius Ambu, wildlife department director of the Malaysian state of Sabah on Borneo island.

He warned that the elephants travel in herds of up to dozens of animals and that still more carcasses could turn up.

"We are trying to comb more areas. My hunch is that there may be more," he told AFP. "I don't think it's an accident."

Ambu said three highly decomposed carcasses were found Wednesday in Sabah's remote Gunung Rara Forest Reserve not far from where officials found the 10 other dead pygmy elephants, a rare sub-species of the Asian elephant.

State officials on Tuesday released photos of the original batch of 10 pachyderms, including a heartbreaking shot of a baby elephant nuzzling its dead mother.

The young elephant appears unharmed and has been taken to a wildlife park in the state, Ambu said.

A chemists' report on the original 10 animals would be completed next week and could reveal what killed them, he added.

Fewer than 2,000 Borneo pygmy elephants, which are smaller and have more rounded features than full-sized Asian elephants, are estimated to be left in the wild.

Activists say deforestation -- for logging and to clear land for agriculture, especially oil palm plantations -- and other human encroachment severely threatens the habitat of the elephants and other endangered Borneo wildlife.

Borneo is a vast island shared by Malaysia, Indonesia and Brunei, whose once-vast rain forests -- considered among the world's richest concentrations of biodiversity -- are dwindling fast.

Wild elephants have steadily been squeezed into smaller forested areas, giving rise to frequent confrontations with humans, but Ambu said the suspected poisoning incident is the first for Sabah.

Poisoning is suspected due to severe ulceration and bleeding found in the animals' digestive tracts, he said.

Dozens of wildlife officials, police and other personnel have been dispatched to comb through the Gunung Rara forest reserve for other possible victims.