The officers discovered the critically-endangered animals - which were in "severe distress" - crammed into cramped boxes in Pekanbaru in West Sumatra.

Sadly one loris had died - believed to have suffocated in the cramped, airless container.

The world's only venomous primate has become popular in recent years thanks to a proliferation of YouTube videos portraying them as cute and cuddly.

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These mass extinctions are often prompted by the illegal wildlife trade.

But the rising demand for slow lorises as pets is pushing the species to the brink of extinction.

Thankfully the animal's teeth were still intact as traffickers cut them off to make them easier to handle.

Dr Karmele Llano Sanchez, programme director of International Animal Rescue (IAR) Indonesia, said: "We urge Facebook to support efforts to stop wildlife trafficking by blocking and reporting Facebook users who advertise or post pictures of protected wildlife.

"This will be a major step in cracking global illegal wildlife trade. If Facebook cares for the creatures on our planet, they must do something to help them."

These mass extinctions are often prompted by the illegal wildlife trade.

In recent years, social network platforms have been increasingly used by wildlife smugglers for their illegal trading activities.

Christine Rattel, programme advisor at IAR Indonesia, said: "With the increased use of social networks for wildlife trafficking, we have also seen an increase in the demand for wildlife and wildlife products by the general public.

"It’s increasingly challenging to tackle wildlife trade networks and it's up to the public to reduce the demand in wildlife and to give all animals a chance to survive in the wild."

Two people were arrested in the raids by the Rapid Response Police Unit (SPORC) of the Environment and Forestry Protection and Law Enforcement Agency.

International Animal Rescue, who accompanied the officers, said in a statement: "The police raids conducted on 20th and 21st September in West Sumatra have dismantled an illegal wildlife cyber-trade network who used Facebook to sell wildlife.

"The two perpetrators were arrested and taken to the police headquarters of West Sumatra."

Slow lorises are protected and listed by the Convention on International Trade in Endangered Species (CITES).

The shy, nocturnal, tree-dwelling animals were about to be sold as pets over the internet, according to IAR. It runs a slow loris rescue centre where they will recover from their plight.

In Indonesia the illegal trade in many protected wildlife species is rampant and is having a devastating impact on already declining wildlife populations.

The rescued slow lorises have been assessed and treated by IAR which has rescued more than 800 since 2008 - most captured for the illegal trade.

Imam Arifin, wildlife veterinarian at IAR Indonesia, said: "The lorises are in reasonable condition, even though they were found in severe distress.

"They still display wild behaviour indicating that they might have been recently captured from the wild. Their teeth are also still intact, so they can be safely released soon."

The animals rescued include a mother and baby. Sadly one loris had died, perhaps as a result of suffocation after being confined in a cramped, airless box by the traffickers.

The surviving lorises will be taken to Kalaweit’s Supayang Gibbon Conservation centre two hours by road from Padang. established in 1999 to care for abused wildlife on Borneo and Sumatra.

Edward Hutapea, head of the Environment and Forestry Protection and Law Enforcement Agency in Pekanbaru, stated: "It is important to tackle these criminal networks to stop wildlife trafficking."

He added that wildlife crime not only relates to people trading in wildlife.

He said: "The illegal keeping of wildlife is also against the law and must be tackled as well."

He urged everyone keeping wildlife as pets to immediately surrender their animals to the authorities.

Those that fail to do so would be charged for illegal possession of protected wildlife.

Mr Hutapea continued: "To keep wildlife in captivity is an activity responsible for the death of many animals that won’t survive for future generations."

Experts have been sounding the alarm over the massive declines in animal species and vast extinction trends across the globe, causing the loss of billions of animal populations in recent decades.

These mass extinctions are often prompted by the illegal wildlife trade.

Dr Sanchez said: “If people want to have wildlife as pets at home, or to watch YouTube videos in which animals are exploited, they must realise this is the one of the main factors behind wildlife trafficking.

"While there is a demand for these animals, we will never be able to stop wildlife trade.”

Two years ago, IAR launched a campaign asking people not to watch YouTube videos portraying slow lorises as pets because they are a protected species in all habitat countries in South East Asia.

The charity also appealed to YouTube to take down those videos which could be responsible for the increase in demand for them as pets and in turn fuelling the illegal pet trade.

Khairul, Investigator of the Environment and Forestry Protection and Law Enforcement Agency, said: "Our agents have taken both the animals and perpetrators into custody and the suspects are liable to prosecution and will receive legal charges."