WASHINGTON – The National Institutes of Health has placed a temporary moratorium on new studies using chimpanzees, it said Thursday in response to a report that marks nearly all medical research on the great apes as scientifically unjustified.

“Effective immediately, NIH will not issue any new awards for chimpanzee research” as the agency puts in place a committee to review research proposals, NIH Director Francis Collins said.

Ongoing chimpanzee research that does not meet rules established by the report will be phased out, Collins added. He estimated that about half of the 37 current NIH-funded chimp studies would not rise to standards proposed in Thursday’s report from the Institute of Medicine.

The congressionally mandated study concluded that future studies using the great apes need to clear a “very high bar,” said Jeffrey Kahn, a bioethicist at Johns Hopkins University, who led the report committee.

The report did not endorse an outright ban on chimp research, but instead outlined restrictive rules.

Chimpanzees’ similarity to humans in intelligence and emotional awareness implies “a moral cost and ethical issues” when mankind’s closest evolutionary cousin is kept captive for invasive medical research, Kahn added.

Chimpanzees are not needed for research on HIV/AIDS, cancer or nearly any other type of disease, the IOM found. The report committee concluded that only one disease might warrant further research with apes: the development of a vaccine to prevent hepatitis C.

But even that conclusion was contentious. Half the 12-member committee of medical experts felt that hepatitis C vaccine research could move forward without testing new vaccines on chimps.

About 3.2 million Americans have the hepatitis C virus, which attacks the liver and often proves fatal. No preventive vaccine exists.

Since 2001, the NIH has funded 110 studies with chimps, including 44 studies for hepatitis, nine for HIV/AIDS, 11 for brain research and 13 projects on genetics.