A critically endangered species of orangutan which lives in one forest in Indonesia is in danger of rapid extinction after a court ruled construction of a new hydro-electric dam can go ahead, despite a legal challenge by environmental groups.

The Tapanuli orangutan (Pongo tapanuliensis) was discovered by scientists in 2017, and just 800 individuals are believed to exist, making it the rarest great ape species on the planet.

But the construction of the Batang Toru Dam in North Sumatra, backed by the Bank of China, as part of the country’s “Belt and Road” infrastructure project, will rip through the orangutan’s habitat.

The state administrative court in North Sumatra’s capital, Medan, ruled construction can continue despite critics of the hydro dam providing evidence that its environmental impact assessment was deeply flawed.

Campaigners said the construction of the dam is also devastating for the Sumatran orangutan which is also critically endangered, threatened by deforestation to make way for palm oil plantations.

Bajau 'sea nomads' of Indonesia Show all 8 1 /8 Bajau 'sea nomads' of Indonesia Bajau 'sea nomads' of Indonesia A Bajau diver hunts fish underwater using a traditional spear A Bajau diver hunts fish underwater using a traditional spear Melissa Ilardo Bajau 'sea nomads' of Indonesia A Bajau diver A Bajau diver hunts fish underwater using a traditional spear Melissa Ilardo Bajau 'sea nomads' of Indonesia The Bajau village of Jaya Bakti The Bajau village of Jaya Bakti Melissa Ilardo Bajau 'sea nomads' of Indonesia Jaya Bakti homes from the water Jaya Bakti homes from the water Melissa Ilardo Bajau 'sea nomads' of Indonesia A Bajau diver displays a traditional wooden diving mask A Bajau diver displays a traditional wooden diving mask Melissa Ilardo Bajau 'sea nomads' of Indonesia A Bajau villager demonstrates the use of traditional wooden goggles A Bajau villager demonstrates the use of traditional wooden goggles Melissa Ilardo Bajau 'sea nomads' of Indonesia A young Bajau girl looks on in excitement as her father, a traditional Bajau diver, returns to Jaya Bakti from a two-week fishing trip A young Bajau girl looks on in excitement as her father, a traditional Bajau diver, returns to Jaya Bakti from a two-week fishing trip Melissa Ilardo Bajau 'sea nomads' of Indonesia A small, unnamed island serves as a haven for visiting Bajau houseboats A small, unnamed island serves as a haven for visiting Bajau houseboats. Melissa Ilardo

A key step towards ensuring the species survives is reconnecting the fragmented forests the primates are spread across.

Announcing the decision of a three-judge panel, presiding judge Jimmy C Pardede said the witnesses and facts presented by the Indonesian Forum for the Environment, the country’s largest environmental group, in its case against the North Sumatra provincial government were irrelevant.

The group, known by its Indonesian acronym Walhi, said it would appeal.

“We will take all available legal channels,” said Dana Prima Tarigan, the group’s executive director for North Sumatra.

“The dam will essentially doom the Tapanuli orangutan species to extinction,” the group said on a petition calling on the Bank of China to end its support for the construction work.

China’s state-owned Sinohydro is building the dam, which is reportedly financed by Chinese loans.

China’s “Belt and Road” project aims to build massive amounts of transport and trade infrastructure across Asia extending the country’s economic and political influence.

The Tapanuli orangutan was found to be a new species in November 2017 after DNA analysis and a field study revealed unique characteristics.

The population, with frizzier hair, significantly different teeth and distinctively long calls for the males, was previously thought to be their close relative, the Sumatran orangutan.

Their diet is also unique, containing unusual items like caterpillars and conifer cones. They have never been observed on the ground, which scientists suggest may be due to the presence of Sumatran tigers in the area, which are also critically endangered.