New Europe-wide controls to regulate experiments on animals are likely to be adopted in the next few months, replacing a 24-year-old EU directive.
For the first time, common rules to protect animals used for scientific research will apply in all 27 EU member states.
"This brings much of the rest of Europe close to the UK's high standards" for animal welfare, Dr Simon Festing, chief executive of the lobby group Understanding Animal Research, told the BBC.
The rules were drawn up by the European Commission, then amended by the European Parliament and the Council, the grouping of EU ministers.
Animal welfare push
With the introduction of the EU's Lisbon Treaty last December, animal welfare became a core EU value, ranking alongside the fight against discrimination, promotion of gender equality and the protection of human health and welfare.
A new EU treaty article says the member states "shall, since animals are sentient beings, pay full regard to the welfare requirements of animals".
It adds the proviso that laws and customs relating to religious rites, cultural traditions and regional heritage will also be respected.
A key principle embedded in the new legislation is the "three Rs" - Replace, Reduce, Refine.
The goals are to replace animals with alternative techniques wherever possible, to reduce the number of animals used in experiments, and to refine experiments as much as possible to minimise suffering.
A difficult area to legislate on is the degree of pain or stress that animals suffer during scientific experiments.
The new draft directive establishes a system to classify the severity of procedures, and examples of "mild", "moderate" and "severe" experiments are given in annexes to the directive.
But Dr Festing says that with humans, the "pain scale" of one to 10 used by doctors is only a rough guide, and with animals the degree of pain is even harder to assess.
In some tests, pain is part of what the researchers want to assess - for example in studying migraine, he says. But in analysis of arthritis, "we don't really want animals to be in pain - we want to give them painkillers".
Samira Gazzane of the anti-vivisection group BUAV says the new directive contains too many exceptions that dilute the restrictions on suffering. "We're very unhappy that some definitions are very unclear," she told the BBC.
Rodents before primates
BUAV and other campaigners against animal testing want a complete ban on experiments on great apes. But the directive will allow them in exceptional circumstances - for example, to research "a life-threatening, debilitating condition endangering human beings".
Monkeys - "non-human primates" - formed only 0.09% of the animals used in scientific tests in the EU in 2005, and no great apes were used.
In contrast, 53% of the procedures were conducted on mice, and rats were the next largest group - 19%, the European Commission reported. The total number of animals used was 12.1 million.
Under the new directive, all projects involving tests on live animals will require prior authorisation from a "competent authority" in each country. Its role will be to evaluate the projects impartially.
There is also a requirement that at least one-third of the testing establishments are inspected each year. And all those using primates will be inspected at least once a year.
Safety testing of chemicals and appliances used by consumers is one of the important areas where animals are often used.
The EU has banned the use of animals to test cosmetics, and 2013 is the target year for ending all marketing in the EU of cosmetics tested on animals. Until then, imported cosmetics with ingredients tested on animals can still be sold in the EU.
But the EU's new legislation to regulate hazardous chemicals - called Reach - might lead to more tests on animals.
According to Dr Festing, it is still unclear what impact Reach will have in this area, "but it's probably quite small compared with the total amount of research".
Meanwhile, the huge expansion of genetics, especially research into the genetic basis of disease, means "the animal numbers are all going up", he says.
With Europe's rapidly ageing population there is increasing demand for tests on non-human primates, among other animals, he says.
The race is on to find treatments for diseases prevalent among the elderly, such as Alzheimer's and Parkinson's.
The development of more specifically targeted medicines also makes primates especially useful because "they are the only animals that share our metabolic pathway," Dr Festing says.
An EU expert panel has argued that testing on primates is still necessary because their immune system is very similar to that of humans. They are needed to develop drugs for malaria, HIV/Aids or emerging killer infections such as Sars, scientists argue.
That view is rejected by the European Coalition to End Animal Experiments (ECEAE), which includes BUAV. It says that numerous tests on primates have failed to produce a viable Aids vaccine, or treatments for Parkinson's, stroke or other life-threatening conditions.
Ms Gazzane of BUAV says the EU needs clear targets for finding alternatives to animal testing.
The new directive aims to foster a culture of data-sharing among researchers, to prevent duplication of experiments on animals.
But experts say there are limits to the degree of transparency that can be expected in this area, not least because some animal rights campaigners have used violent methods in the past.
Europe's diversity - cultural and linguistic - may also be a barrier to transparency.
Animal testing is totally unnecessary and should be banned. More money should be spent on alternative methods for medical testing.
Bev Hughes, Bristol, UK
This is a great day for animals. A huge first step in the right direction. Kudos to the EU for speaking for those who can't speak for themselves. I hope the rest of the world will follow in your footsteps. I don't envy the people who are forced to choose which testing is "animal worthy". I think a ban on all cosmetics tested on animals is an excellent step. Now how do we get the governments to look at unnecessary distress and harm that goes undetected in slaughterhouses?
It's worth stressing that this new European law is not as strict as the current British law. Research animals in Britain still have a higher standard of welfare than anywhere else in the world which is why it is much better such work is done here rather than abroad.
Peter, Notts, UK
I say "no" to the use of animals in such cruel experiments. I consider that is both ethical and scientifically unjustifiable.
Martha Sanz-Degerth, Helsinki, Finland
No-one wants to use animals in research. They are just the only option we have at the moment. Science is currently stuck in a Catch-22. In order to increase our understanding of human systems, we must design models of human systems. The design of models, however, requires that we understand human systems. Yes, using animals in research is an evil, but if we want to continue to make discoveries that, directly or indirectly, benefit our search for medicines and cures, then it is a necessary evil, at least for the moment. As for those who campaign for the abolition of animal research, I hardly see them suggesting viable alternatives! I have no respect for militant animal rights activists that would happily firebomb a scientist's house or break into a lab and destroy months of constructive research. By all means preach equality, but there is such a thing as taking it too far.
N, Reading, UK
I am so happy that the EU is working on a legislation against testing on animals. I want it to be completely banned as it is not acceptable. I am pretty sure that the new technology can help assess the risks of any products.
Jenny, London, UK
I agree provided: animal welfare is safeguarded, testing is limited to research on diseases and genetic disorders, not cosmetics application.
Mary-Rose Van Rolleghem, Brussels, Belgium
Ninety two percent of new drugs fail in clinical trials, after they have passed all the safety tests in animals. Many drugs that reach the market are later withdrawn or relabelled because of serious side effects. Reliance on animal data allows companies to avoid the expense of bigger and better clinical trials.
Mike Donnelly, Liverpool, UK
There is no reason, nor excurse that any animal with a brain and feelings as well as a face should suffer for humans' wellbeing. Medical research must find other possibilities. All animal testing should and must be forbidden.
Charlotte Vallner, Roscof, France
My understanding is that some animal testing is compulsory for drugs and human cleaning products, like shampoo. I would never agree to using animal for testing. Controls are most certainly needed and I am grateful for the work groups like BUAV do. Can't humans, even small children, close their eyes when having their hair washed? How many ingredients need continuous testing? It's ludicrous. It's also barbaric. Time to end this cruelty. People, please seek out products not tested on animals. Personally, I would not want to prolong my life with drugs created through testing on animals.
Sarah, Ireland and Glasgow