An orangutan has died after being found on a palm oil plantation in Borneo with 40 air-rifle pellets in her body, an animal protection group said on Friday (Dec 5).

The adult female was found on Wednesday in a critical condition inside a palm oil plantation in the Central Kalimantan province, the Borneo Orangutan Survival Foundation said in a press release.

The case is the latest example of one of the critically-endangered primates being killed by humans. Orangutans are faced with extinction from poaching and the rapid destruction of their forest habitat, driven largely by land clearance for palm oil and paper plantations.

"An x-ray result showed 10 pellets in the head, 8 pellets in the left leg and pelvis, 18 pellets in the right leg and pelvis, as well as six pellets in the chest and right hand," it said.

The primate's right upper leg was also broken and maggots were found inside her open wounds. She also very skinny due to malnutrition.

A team of medics operated on the orangutan in an attempt to save her life but she died on Thursday, the foundation said. The group estimates that the attack took place three days before she was found.

"This added a long list of conflict between between industry and wildlife, as well as (the) practice of nature exploitation," it said, urging Indonesian government to take a real action to protect the primates.

"The BOS Foundation urged real commitment and action of government, private sector in protecting orangutan," it said.

Orangutans are native to the vast island of Borneo, which is shared among Indonesia, Malaysia and Brunei. Destruction of Indonesia's lowland rainforest and peatland for palm oil plantations and agriculture has led to a dramatic decline in the number of orangutans, Asia's only great ape.