WASHINGTON – The federal government on Friday boosted protections for chimpanzees, formally declaring both captive and wild populations of the primates as endangered.

The action, from the U.S. Fish and Wildlife Service, comes in response to a 2010 petition that prodded the agency to classify chimps in captivity the same way they did chimps in the wild. The petition was part of a long-running campaign by animal rights activists to increase the protections for the animals that are among humans' closest genetic cousins.

Famed chimp researcher Jane Goodall said on her website: "I feel very relieved that all chimpanzees, whether they are captive or wild, will be listed as endangered."

She added that "there is still much to be done" in protecting chimps. "But this new listing is a huge step towards preventing much of the blatant exploitation that was possible before," she said.

According to the Humane Society of the United States, an animal welfare organization, there are an estimated 172,000 to 300,000 chimpanzees still in African rain forests; they have been classified as endangered. The 1,724 in captivity in the U.S. have been classified as threatened, giving greater leeway to allowing their use in biomedical research and the entertainment and pet industries.

Friday's rule, which will be effective in September, means that anyone who wants to use chimps in the United States in harmful ways will have to show that the use will benefit the conservation of the species, the Humane Society said. They will also have to receive permits to do so.

"Hopefully, this sends a strong signal to not even attempt to use these animals," Jonathan Lovvorn, the Humane Society's chief counsel, said in a statement. He further called it "another barrier to using chimpanzees" and said it provided momentum to efforts to retire the animals completely from research.

The use of chimpanzees in biomedical research was once commonplace but has been curtailed because of the ethics of using animals so similar to humans in captive experiments and because scientists began to question the effectiveness of doing so. While chimps are genetically close to humans, there are enough differences that research on chimps doesn't necessarily translate to humans.

Beyond that, laboratory advances mean that knowledge once gained only by examining a live animal now can be learned in a petri dish.