The Humane Society of the United States, a leading conservation group, has accused the Smithsonian Institution of encouraging sports hunters to kill endangered species because the museum often wants the hard-to-find animals for research and exhibition.

Officials at the Smithsonian have flatly denied that their broad interest in all kinds of animal life is a signal to sportsmen to track down rare animals. At the same time, Smithsonian officials are actively interested in finding out whether they can import a rare Kara-Tau sheep from Central Asia and three other sheep that were killed by the museum's No. 1 donor. The animals are officially listed as endangered species.

"The issue here is that trophy hunters are more likely to kill endangered animals when they can import them by passing them through U.S. scientific institutions, or by having them displayed at the museum," said Wayne Pacelle, the senior vice president of the Washington-based Humane Society. The National Museum of Natural History, which has 250 research scientists and 120 million specimens, the largest collection of any Smithsonian museum, is usually the destination of animal specimens.

The latest flap, reported in Wednesday's New York Times, has arisen over the proposed donation of the endangered sheep by Kenneth Behring, a California businessman and well-known game hunter. Behring gave the Smithsonian its largest gift to date of $20 million, and the museum is examining 200 specimens from his collection for its research and educational programs. The sheep in question were shot by Behring in Kazakhstan in the fall of 1997, weeks before his donation to the museum. The agreement covering the monetary donation clearly states that the museum would not accept any animals Behring collected after the gift.

"Sport hunting is legal, and the only time the Smithsonian will accept an animal is if all the legalities have been met. We do not encourage sport hunting," said Randall Kremer, a spokesman for the Natural History museum. "It is also ironic that research done by scientists at this museum helped to form the basis for this animal's classification as endangered in the first place."

In September 1998, Robert S. Hoffman, the senior scientist at the museum, asked the U.S. Fish and Wildlife Service for permission to import the animals, a normal procedure. On his list was the Kara-Tau, whose population is estimated at only 100.

When the hunt took place, in the fall of 1997, the sheep was endangered. Shortly after the hunt, the sheep's status was upgraded to an even higher classification, "critically endangered." Currently, that specimen, and the three other sheep, are in a taxidermy shop in Edmonton, Alberta. The application became inactive when the Smithsonian did not receive documentation Fish and Wildlife needed from the Russian federation government.

Smithsonian officials, who have said the rare animals would add an important scientific record to their collection, are waiting for new information that Fish and Wildlife requested before the scientists decide whether to renew the request.

Behring released a statement that said the sheep were killed legally, were not an endangered species in Russia at that time, and "will go to a museum in Spain if the U.S. does not wish to import them. Where they go is not important to me so long as they are in the hands of responsible scientists, and I was certainly not encouraged by any museum to hunt them or offer them the specimens or donate the specimens to any museum."

Pacelle of the Humane Society said the group was concerned about the sheep "because this is not the first time the Smithsonian has become mixed up with trophy hunters." In the late 1980s and early '90s the museum was embroiled in a controversy when a Fish and Wildlife employee, who was working at the Smithsonian, was found guilty of smuggling four argali -- large white sheep -- from China. Another contretemps arose more recently over three other argali, which the government permitted the Smithsonian to import.

The conservation group is also raising questions about Behring's participation in a hunting expedition in Mozambique last July that killed three bull elephants. Behring has said his group followed all the regulations in Mozambique and were accompanied by government officials.

Pacelle said he is wary. "In this case it has the appearance of a quid pro quo and it was an individual who may have violated the game laws of a country after associating himself with the Smithsonian," he said.

CAPTION: Big-game hunter and big-bucks businessman Kenneth Behring at the National Museum of Natural History.