Today, Tuesday 24 April, is the UN-recognised World Day for Animals in Laboratories, when the public is encouraged to consider the plight of the hundreds of millions of animals exploited, and often killed, in toxicity tests and disease research. There are serious humanitarian and scientific issues at stake.

In a bid to mimic the effects of Parkinson's disease, a London medical research team injected 22 marmoset monkeys with a potent brain poison every day for five days. After the last dose, none was able to move. They sat hunched, mute and rigid in their cages, so severely disabled that they had to be hand-fed. The monkeys were then given the illegal party drug Ecstasy in the hope that it might provide insights into chemical pathways within the brain. None of this research proved beneficial to humans; rendering the suffering of the monkeys valueless.

This experiment was part funded by the medical charity Parkinson's UK. Unsurprisingly, it is not keen for the effects of this research on the monkeys to be publicly known.

As a campaigner for human rights, I am no stranger to cover-up and whitewash, and to the desire of those with power to wield it without public scrutiny. A disturbing desire for secrecy about animal experiments is shared by a number of respected, high-profile medical charities, including the British Heart Foundation, Cancer Research UK and the Alzheimer's Society. They have an annual turnover of hundreds of millions of pounds, all donated by the generous British public. Yet when seeking donations, their funding of animal experimentation is not something they publicise or want to discuss.

This reticence is understandable. A NOP poll last year, commissioned by Animal Aid (of which I am a patron), found that 82% of British people "would not donate to research charities that fund animal experiments."

Many past and current donors might be surprised to learn that some of their favourite charities persist in financing animal research that involves suffering and produces results in other species that are often irrelevant to diseases in humans. This is because people and animals have a different physiology. A drug treatment that works in dogs or cats may not work in humans (and vice versa).

Public donations finance research procedures like mice being grafted with tumours, even though such primitive techniques do little to replicate the real disease in people. Other mice have their immune systems destroyed by genetic tinkering and are then injected with cancer cells and force-fed experimental drugs. These lab experiments cause animal suffering, and produce relatively little data that is applicable to combating cancer in humans.

Charity-funded research into heart disease involves grievously injuring dogs, pigs, rabbits, goats, rats and mice to produce models of heart disease that are, in fact, very different from those experienced by human patients. Even some scientists are beginning to question the value of animal experiments.

The charities would prefer this information to remain hidden. Animal Aid has attempted to get from them details about how many animals have been used in the research that they fund and the nature of those experiments. The charities have been mostly evasive. If they have nothing hide, why aren't they open and transparent?

In an effort to get the research made public, Animal Aid wrote, in January this year, to the four above-mentioned charities, inviting them to debate the moral and scientific issues underlying the use of animals in the research they fund. None of the charities even replied to the invitation.

This stonewalling shows a disregard for the public's right to make an informed decision about which charities they donate to. Unlike the animal experiments that are funded by universities and drug companies, the research funded by charities is dependent on the public making a conscious decision to part with their hard-earned cash.

As a matter of public accountability, the charities should declare how much of their budget is spent on animal research, the nature of the experiments and the species, number and source of the animals used. The results of the research, including any medical benefits gained, should be published in terms that are specific, rather than rhetorical or speculative.

The public can then assess whether the suffering inflicted is justified and whether the research produces any tangible medical progress.

On the available evidence, despite millions of pounds being poured into animal-based experimentation, the practical benefits to patients are rather slim. Using 'animal models' of human diseases involves mere approximations. How new drug treatments work in lab rats is not a reliable indicator of how they will work in people. We are not rats.

Experimental cancer drugs, often developed using mice with crude genetic alterations, almost always fail in human trials. Heart-damaged rabbits showed cardiac improvements when injected with bone marrow stem cells, but trials in people continue to disappoint. Mouse models of Alzheimer's have been mostly useless in developing new treatments. Experimental drugs like dimebon, tarenflurbil, tramiprosate, semagacestat, and bapineuzemab all worked on animals but failed in people.

A growing number of medical researchers are aware that animal experiments are a poor guide to human diseases and treatments. They, consequently, reject them and concentrate on a range of human-based research techniques, such as donated tissue and organs, cell cultures, computer modelling and scanning and the still vital methods of clinical observation, autopsy studies and epidemiology. Some of these alternatives have been used by the Dr Hadwen Trust for Humane Research to secure medical progress in understanding a range of illnesses, including HIV, diabetes, breast cancer, asthma, meningitis and liver disease. It gets results that are directly applicable to humans, without causing animal suffering.

The generous public have a right to know if their donations are being used to fund animal research. Secrecy is not justified when the lives of so many species, including our own, are on the line.