The National Institutes of Health will curb its use of chimpanzees in medical and behavioral research, NIH Director Dr. Francis Collins announced Thursday.
Collins said in a news conference that the agency would temporarily bar all new research projects using chimpanzees, and that all current projects involving the primates would be evaluated.
The announcement came after an Institute of Medicine report issued on Thursday that called for strict limits on the use of chimpanzees - the closest genetic relatives to humans - in medical and behavioral research.
In its report, the IOM said experiments on chimpanzees had not advanced research enough to justify their continued use in invasive experiments.
"The committee concluded that research using animals that are so closely related to humans should not proceed unless it offers insights not possible with other animal models and unless it is of sufficient scientific or health value to offset the moral costs," Jeffrey Kahn, chairman of the IOM committee, said in a news release. "We found very few cases that satisfy these criteria."
Of the nearly 1,000 chimpanzees currently housed in U.S. research facilities, the NIH owns 612 of them. Collins said many of those animals are not involved in research currently.
The NIH will begin reviewing the 37 federally funded projects that involve chimpanzees. Collins estimated that 50 percent of the projects will not meet the IOM's criteria and will be phased out or ended immediately.
Chimpanzees are viewed as more accurate models for how diseases and treatments develop in people than other animals, such as mice .
But because chimps share some behavioral characteristics with humans, many scientists and animal rights activists have concluded that experimenting on them is unethical.
Scientists have used chimps to develop vaccines and treatments for HIV, hepatitis B and hepatitis C, and the IOM report said private research companies have used the animals to test drug safety and efficacy.
The U.S. is one of only two countries that conduct invasive research on chimpanzees; the other is Gabon in central Africa.