Ministers should not rule out the possibility of allowing apes to be used in experiments, the head of the UK's Medical Research Council has said.
Licences are not currently given for tests on the great apes
In 1997, the government said it would never approve ape research because they were too similar to humans, but there is no law prohibiting the practice.
Professor Colin Blakemore said such research was "essential" if it was the only way to cure a particular disease.
Animal welfare groups want a ban on all primate testing in Britain.
Professor Blakemore's comments came as campaigners for and against animal testing staged two separate protests in the row over Oxford University's new £20m animal research laboratory.
Supporters of animal testing were holding a rally in Oxford, while anti-vivisection campaigners were demonstrating in Moreton-in-Marsh, Gloucestershire.
Currently 2,800 non-human primates are used in medical research, but the Royal Society and the Academy of Medical Sciences are assessing whether genetically modified rats and mice could be used instead.
A group of leading scientists has defended the use of primates in a booklet - Primates in Medical Research - which was published jointly by the MRC and the Wellcome Trust.
Professor Blakemore told BBC Radio 4's Today programme it was "not surprising" that many people were against research, as they were constantly told it was "unbelievably cruel" and "achieved nothing".
He added: "What we have seen in the last few years, against a background of ridiculous extremism, is more willingness to discuss openly when and where some animal research is necessary.
"The public have listened. They don't like the idea. Who does? But they have realised that it is essential."
He said the final test for any drug or treatment had to be on humans, but added that 60% of potential drugs were rejected at the animal testing stage.
These experiments are investigating diseases and conditions such as Parkinson's, obsessive compulsive disorder, schizophrenia, HIV and strokes.
However, the British Union for the Abolition of Vivisection (Buav) is publishing a report, due out on Monday, which calls for a ban on testing on any non-human primates.
The publication has been backed by the world famous primatologist Jane Goodall, who described the testing as "unethical".
She said: "In reality, most people do not know - and do not want to know - the grim reality of what happens to non-human primates in laboratories.
"Not only are many experiments on them unethical, many are unnecessary; and their results may be misleading because they were developed at a time when scientists knew little about the effect of stress on the immune system."
Professor Sandy Thomas, director of the Nuffield Council on Bioethics, said: "It is important to be aware that research involving the great apes, such as gorillas, chimpanzees and orangutans, is not prohibited directly by law.
"However, licences for this type of research are not granted as a matter of current Home Office policy.
"The emergence of new diseases may mean that a reassessment of this policy is required in the future. On the other hand, the continued development of non-animal methods for research may mean that alternatives could be available," said Professor Thomas.
"It is important that the necessity, usefulness and relevance of specific types of animal research are ascertained in each individual case."