WASHINGTON • The National Institutes of Health said Thursday that it would curtail its use of chimpanzees in medical research, suspending new chimp research grants and agreeing to accept the recommendations of an outside panel that found the apes are "not necessary for most biomedical research."

NIH Director Francis Collins said he'd decided to accept the recommendations of the Institute of Medicine, which had weighed in earlier Thursday on the contentious issue of whether chimps — one of man's closest genetic cousins — should be used to help medical researchers understand and combat human disease.

The panel decided that most of the time, the answer was no.

The NIH's Collins said he would follow their guidance.

"I think it was a very thoughtful set of recommendations from a distinguished group of experts who spent many months taking in input from lots of different perspectives," said Collins, who oversees the nation's premier biomedical research facility, based in Bethesda, Md. "I found their recommendations very compelling and scientifically rigorous."

Animal rights activists generally cheered the institute's report and the NIH's reaction to it.

Though neither institution went as far as the outright ban on chimp research that activists desired, they did acknowledged that science was moving away from chimps as a necessary research model.

"The NIH has funded a lot of research that's just been deemed unnecessary," said Jarrod Bailey, the science director for the chimp-release campaign of the anti-animal testing New England Anti-Vivisection Society.

"Even though they have stopped short of the ban, it's a welcome first step."

After reviewing the current state of science and the demand for chimps in research, the institute concluded that changes in science "have rendered chimpanzees largely nonessential as research subjects."

The 190-page report didn't rule out chimps for research, saying there are some situations in which they still could prove useful. Beyond that, chimp experimentation could be indicated in later years if new diseases emerge.

For the most part, however, the panel determined that chimps as research subjects weren't as valuable as they once were.

"Science is evolving. We have alternative ways of testing drugs," said committee member Warner Greene, the director of the Gladstone Institute of Virology and Immunology at the University of California, San Francisco.

He noted that the last two blockbuster hepatitis drugs were produced without using chimpanzees, and said that under the committee's new guidelines "many existing studies that use chimps would not clear the bar."

The NIH, which funds much of the nation's chimp research, had said previously that using the animals was crucial to understanding and combating diseases, particularly hepatitis C.

More than 900 chimps live at main research labs in the U.S. Though the number of chimpanzee experiments at any time is small, the chimps have lived a lifetime of research that involves dart-gun knock-downs, biopsies and repeated infections.

On Thursday, the NIH said it would appoint a committee to implement the institute's recommendations.

The NIH won't issue any new awards for research that involves chimpanzees until that review is complete.