The National Institutes of Health, America's foremost medical research agency, said it would no longer fund studies involving chimpanzees as it prepares to revise its policies using the primates.
The NIH said it plans to review all ongoing studies using chimpanzees, although such projects already are rare. Of the 94 000 NIH-funded projects in 2011, only 53 used the primates.
"While used very selectively and in limited numbers for medical research, chimpanzees have served an important role in advancing human health in the past," the NIH said in a statement.
"However, new methods and technologies developed by the biomedical community have provided alternatives to the use of chimpanzees in several areas of research," it said.
Many countries have banned chimp research
The United States is the only industrialised country still using primates for medical research, in particular for studies covering hepatitis C, Aids, and malaria.
The European Union formally forbade the practice in 2010, following Japan, Australia and other developed countries.
In 2010, an NIH proposal to reintroduce 200 retired chimpanzees into research colonies caused public outcry.
The controversy prompted the agency to ask for a review of chimp research by the Institute of Medicine (IOM) an independent, nonprofit organisation that aims to provide unbiased, authoritative advice to decision makers and the public about health matters.
The NIH said it has accepted recommendations from an IOM panel to stop funding research with chimps, while it revises its policy.
In a 2011 report, the IOM stopped short of urging an outright ban, but it called for research on chimpanzees to continue only if there is no other subject available, if the research could not be performed ethically on humans, and if failure to do so would hinder progress against life-threatening conditions.
The IOM concluded that most scientific experiments conducted on chimps are not indispensable.
"The committee concludes that while the chimpanzee has been a valuable animal model in the past, most current biomedical research use of chimpanzees is not necessary," the IOM said.
But chimpanzees may still be necessary in the development of vaccines against hepatitis C, for short-term continued study of monoclonal antibody research against bacteria and viruses, comparative genome studies and behavioural research, the report said.
The panel recommended that the animals should be kept in their natural habitat or environments that mimic it.
There were 937 chimpanzees in US research labs in 2011, including around 450 supported by the government. The rest were owned and used for research by private industry.
The IOM noted that the NIH called for a moratorium on breeding chimps for research back in 1995, and said that as a result, the federally-funded research population will "largely cease to exist" by 2037.
(Sapa, January 2013)