Distressing footage has emerged purporting to show horrific conditions suffered by monkeys at Europe's largest primate research centre.

Activists from Animal Defenders International (ADI) claim to have recorded the film using hidden cameras at Biomedical Primate Research Centre in the Netherlands.

In the video, stressed monkeys can be seen getting drugged and tattooed so they can be used in experiments.

Animal campaigners have captured shocking video of what they say are conditions suffered by monkeys at the Biomedical Primate Research Centre in the Netherlands (pictured, a monkey is tattooed while under sedation)

Video shows the monkeys being sedated for use in experiments but not completely knocked out, so they remain conscious and able to feel (pictured, a monkey has experiments done on its eyes while sedated but conscious)

Campaigners say the primates - mostly macaques - are kept in barren cages before experiments (pictured) which causes significant stress

Campaigners say some were severely injured after their stressed cage-mates lashed out after being unable to cope with their surroundings.

Some were so stressed that they suffered rectal prolapse, the activists said.

While the monkeys were sedated during procedures such as tattooing, they remained conscious and able to feel - though it isn't clear to what extent.

Primates coming round from sedation were left unattended in a groggy state making them vulnerable to injury, ADI said.

When they were no longer of use for experiments monkeys were put down in full view of their cage-mates, causing fear and distress, it is alleged.

ADI said the monkeys were obviously fearful of their captors and what was happening to them.

Jane Goodall, the UN Messenger of Peace and Founder of the Jane Goodall Institute said: 'The way they are being treated in the video is shocking and inhumane.

'It is my considered opinion that those involved in this kind of research on primates should consider using alternative procedures that do not involve experimentation on intelligent, sentient beings.

'This research should be phased out as soon as possible.'

The primates are obviously afraid of their surroundings and their captors and suffer so much stress they become ill, the activists said (pictured, a struggling monkey is injected with sedative before experiments are carried out)

The footage was captured in March 2017 using a hidden camera and released on September 1, causing public backlash (pictured, workers examine monkeys kept in tiny cages)

A baby macaque recovers from being sedated while unwatched by workers, putting it at risk from injury in its confused state

The Biomedical Primate Research Centre is Europe's largest facility, breeding animals for its own use and other laboratories, collaborating with researchers in the UK and the US.

Latest figures show that it has reportedly more than trebled its primate use, from 95 individuals in 2016 to 317 in 2017.

The facility has 1,600 primates, most of which are macaques kept in breeding groups of 20-40 individuals.

When they are taken to be used in research for diseases they are housed alone in small barren cages. At the end of the experiments they are killed.

The footage was recorded in March 2017 and released on September 1 this year, which is international primate day.

The findings of ADI's investigation has caused outcry, particularly in the Netherlands where there has been widespread media coverage, questions raised in parliament and calls to close down the facility.

The video has also been shown in the European Parliament at a meeting of the Intergroup on the Welfare and Conservation of Animals, where the use of primates and other animals in neuroscience research was discussed.

ADI is calling for the use of primates to be phased out. The European Parliament adopted a resolution promising change 11 years ago, but has never published a timetable for its implementation.

A young macaque is carried by workers so it can be sedated for use in experiments

The macaques are kept in breeding groups of between 20 and 40 individuals, but often become so stressed they lash out and cause severe injuries (pictured, an injured monkey)

Jane Goodall, the UN Messenger of Peace, said experiments on monkeys should be phased out in favour of advanced techniques which can be used on humans

Primates are mainly used to test drugs and typically endure force-feeding or injections of experimental compounds while strapped down in restraint chairs.

Campaigners say that tests in primates and other animals have been shown to produce results which differ from those seen in humans.

Replacing primates with more sophisticated human-based techniques would provide results which are more relevant to people, the activists say.

Jan Creamer, President of Animal Defenders International said: 'Given the known species differences between primates and humans, there can be no scientific or ethical justification for continuing to use primates in this kind of research.

'The move to advanced scientific techniques is good for science and ends the suffering.'

Mail Online contacted Biomedical Primate Research Centre for comment but had not received a response at the time of publication.