Medical research on great apes might be necessary to help find cures for diseases, say a group of scientists.
The study found that testing on chimps, orang-utans and gorillas might be needed if it was the only way to find out how to treat a particular illness.
In 1997 the government said it would never agree to using apes in tests because they are too similar to people and the tests might cause suffering.
Animal welfare groups want a ban on all primate testing in Britain.
Professor Colin Blakemore of the Medical Research Council said the government should think again about using apes because they are so like humans the research has a good chance of being accurate.
Using great apes - but not monkeys - for medical research was banned in Britain in 1998.