The BBC was given access to a laboratory which tests on primates
A Scottish MEP has called for a proposed ban on primate testing to be extended to include monkeys used in Scottish laboratories.
Labour MEP David Martin said Scotland runs proportionately more tests on primates than any country in the EU.
He said testing on monkeys was immoral when other options could be developed.
But scientists funded by the Medical Research Council said primates were only used when there was no alternative.
The BBC was given access to an animal testing centre in the Lothians where a colony of small monkeys are bred in captivity specifically for scientific research.
They are housed in small family groups with access to rooftop runs and free to move around their rooms and cages except during training, cleaning and scientific procedures.
Primates are our closest living relatives - they feel pain and are more sensitive than any other group of animals and I just think it's wrong morally to use them in experiments
David Martin MEP
Once the animals reach maturity at 18 months they are paired up for testing.
This can involve injections of fertility drugs and the removal of blood samples.
When the trial is complete they are put down.
The research is used by scientists trying to develop cures for infertility, contraception, miscarriages and many different kinds of cancer.
The EU wants to ban laboratory tests on chimpanzees, gorillas and orang-utans.
But the ban would not extend to small monkeys.
Professor Bob Millar, director of the Human Reproductive Sciences Unit, said the council never used apes and insisted testing small monkeys was only done because there was no alternative.
He said: "The vast majority of the work that we and other laboratories do is not on living animals, much of the work is done on cells and straight molecules.
"But there are some answers which are very difficult to do on anything other than a primate.
Prof Bob Millar says testing on monkeys remains important
"For example, the primates are a menstruating species so many things to do with women's health, it is not possible to do with a rat or a sheep, you have to do them with a primate."
But Mr Martin said he wanted to see testing on monkeys banned.
He said: "It's Scotland's shame because one in 10 of Europe's experiments on primates is conducted here. We have a population of five million, Europe has a population of 500 million, so proportionately it should be one in 100 - but one in 10 of all experiments are conducted here in Scotland.
"Primates are our closest living relatives. They feel pain and are more sensitive than any other group of animals and I just think it's wrong morally to use them in experiments.
"But secondly, there has been a number of serious scientific reports recently saying that despite their closeness to us in many ways, they actually give very misleading results."
Alternatives to animal testing are being developed in Scotland, funded by the National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs).
Glasgow University does not carry out testing on primates and Sue Barnett, a professor of cellular neurosciences at the university, said they were working on ways to cure spinal injuries without using animals.
She said: "We are developing new ways of using less animals by taking tissue from animals and placing it into culture. And this allows us to grow many more cells and take many more combinations of approach to study these cells than you would do with an animal. And it allows us not to experiment on an animal at all."
Scientists at the Medical Research Council said if a total ban on primate testing was introduced in the EU, their potentially life saving science would have to be completed elsewhere and Scotland would lose some of this work to India or Kenya.
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