The carcasses of the elephants, aged between one and 37, were discovered at different locations in Sabah, local Wildlife Department director Augustine Tuuga told AFP.

“We are currently conducting tests on their internal organs,” he said, adding the carcasses did not have any signs of gunshot wounds.

Tuuga said the elephants could have accidentally consumed fertiliser in the palm oil plantations, which could have poisoned them.

The Star newspaper, citing conservationists, said the creatures might have drunk from poisoned watering holes.

There are about 2,000 pygmy elephants, the smallest type of elephants in Asia, in the wild. Late last year, three were killed by poachers.

In 2013, 14 pygmy elephants were found dead in Sabah and were thought to have been poisoned.

They are threatened by widespread logging of their natural habitat to make way for lucrative oil palm plantations, and are targeted by poachers as their ivory fetches a high price on the black market.

The pygmy elephants are baby-faced with oversized ears, plump bellies and tails so long they sometimes drag on the ground as they walk.