JAKARTA, Indonesia -- Palm oil plantation workers killed and ate a critically endangered orangutan on the island of Borneo, according to an Indonesian lawmaker who called for police to investigate what is a frequent but rarely prosecuted crime.

Daniel Johan said Tuesday the workers shot the great ape after it ventured onto a plantation in a remote area of Central Kalimantan province, probably looking for crops to eat.

"It's a blatant offence against Indonesia's conservation laws," said Johan. "Police have to investigate this cruel action."

Photos of the butchered orangutan provided by a witness show the beheaded animal sprawled on the ground next to a man holding a rifle. One picture showed the orangutan's head floating in a pot. In another, several people are cutting up the primate's flesh.

Last July, the International Union for Conservation of Nature classified Borneo's orangutans as critically endangered. It estimates their numbers have dropped by nearly two-thirds since the early 1970s and will further decline to 47,000 by 2025.

The animals are often killed for their meat or to prevent damage to crops, a crime that can result in five years' imprisonment, but prosecutions are infrequent. Their forest habitat has shrunk dramatically over the past half century, a victim of Indonesia's rush to supply the world with timber, pulp, paper, and more recently, palm oil.

Johan said he asked the witness to report the incident to police but the person feared reprisals.

He said the plantation where the orangutan was killed is owned by PT. Susantri Permai. It is a unit of Genting Plantations Bhd., a Malaysia-based palm oil company.

In 2011, two Indonesian plantation workers admitted to killing at least 20 orangutans and proboscis monkeys for landowners looking to protect their crops.