The US National Institutes of Health, the world's largest funder of biomedical research, has announced it is to "substantially reduce" the use of chimpanzees in the research it funds.

The decision comes after an Institute of Medicine (IOM) report concluded that most research using the apes is "unnecessary".

"Americans have benefited greatly from the chimpanzees' service to biomedical research, but new scientific methods and technologies have rendered their use in research largely unnecessary," said NIH director Francis S Collins.

"Their likeness to humans has made them uniquely valuable for certain types of research, but also demands greater justification for their use. After extensive consideration with the expert guidance of many, I am confident that greatly reducing their use in biomedical research is scientifically sound and the right thing to do."

A small number of chimpanzees will be retained, but not bred, for future research that meets IMO criteria. NIH chimp research projects not meeting the criteria will be wound down, and the majority of NIH chimpanzees deemed "unnecessary" will be retired to federal sanctuaries. Some of the recommendations made by the IMO were rejected, such as the amount of living space needed – 93 square metres per chimpanzee – due to "lack of scientific consensus".

The move follows recent proposals by the US Fish and Wildlife Service (FWS) to list all chimpanzees as endangered following a legal petition from a coalition of organisations. Currently, wild chimpanzees are listed as "endangered" on the US Endangered Species Act, but captive chimps' "threatened" status offers them less protection and allows them to be used for research, entertainment and pets.

Reclassification would mean stricter regulations around use of the apes, affecting both NIH- and privately funded research, meaning further revisions to NIH policy may be needed when a final decision on classification is made.

The US is the only remaining nation in the developed world that still uses great apes as research subjects, though the use of monkeys is still common in the US, Europe and many other parts of the world.

Dr Allyson J Bennett, a spokesperson for animal research advocacy group Speaking of Research and a developmental psychobiologist who uses non-human primates, said that animal research remains an important part of scientific discovery and new understanding that improves both human and animal health.

"We welcome the NIH proposals to reduce the number of chimpanzees in experiments while still ensuring a small number are available for lifesaving research," she said. "We hope that the implementation of the IOM proposals ensures a high standard of long-term care for the chimpanzees, both in research and retirement facilities."

Anti-vivisection groups have expressed disappointment that some chimps will be retained. BUAV chief executive Michelle Thew said that while the animal rights group welcomes the NIH announcement, it is "extremely disappointed that up to 50 chimpanzees will be 'retained' and remain available for future research requests. The psychological and physical harm to the animals, and the scientific ineffectiveness of their use in experiments demonstrate that there should be a total ban on the use of chimpanzees in research."