WASHINGTON (AP) _ Environmental groups and cancer researchers asked Wednesday for federal protection for the Pacific yew, a tree with bark that provides a scarce new cancer-fighting drug.

The petition to Interior Secretary Manuel Lujan could open a new front in the battle over logging in the old-growth forests of the Pacific Northwest, which so far has focused on protecting the northern spotted owl.

Timber industry officials say proposed limits on logging to save the owl could wipe out thousands of jobs.

''In deciding the future of the ancient forests of the Pacific Northwest, more than owls and jobs is at stake,'' Michael Bean of the Environmental Defense Fund said at a news conference. ''Human welfare is vitally at stake.''

Officials of the industry and the U.S. Forest Service, however, said the Pacific yew, or taxus brevifolia, is so abundant it needs no special protection.

A wide-ranging plant screening program sponsored by the National Cancer Institute in the 1960s found the first indications that an extract of the Pacific yew's bark could be used against cancer. The active chemical compound later was isolated and called taxol.

In recent clinical trials, taxol has been effective in a third of women whose ovarian cancer did not respond to conventional treatment, said Dr. William P. McGuire of the Johns Hopkins Oncology Center. It also has promise for treating some other kinds of cancer.

But taxol is in very short supply, with researchers reporting current supplies sufficient to treat perhaps 200 to 300 patients. Efforts to synthesize the drug have not worked.

About 20,000 women are diagnosed with ovarian cancer each year in the United States, and the cancer society said about 12,000 are expected to die of the disease this year.

''We are in a bind at this point as to where we're going to get this drug,'' McGuire said. ''I think we need to save every ounce of this bark that we can.''

McGuire and Susan B. Horwitz of the Albert Einstein College of Medicine, who conducted pioneering studies on taxol, joined the environmental groups in signing the petition. The American Cancer Society sent a separate letter backing the proposal.

The petition to Lujan, asking him to list the Pacific yew as threatened under the Endangered Species Act, says its primary habitat is the old-growth forest. The tree is described as one of the slowest-growing species in the world, thriving in the shady undergrowth of ancient pines.

If the yew were listed as threatened, federal agencies would be required to make sure any timber sales they approved did not endanger the tree.

The yews could, however, be cut to obtain bark needed to make taxol, possibly at the same time as more commercially valuable trees in the same forests are logged.

The petition said there appears to be a short-term need for about 600,000 large yew trees to develop taxol to treat ovarian cancer, while only about 685,000 yew trees greater than 10 inches in diameter remain on non-federal lands in California, Oregon and Washington.

''The status of the species on U.S. Forest Service lands is also precarious,'' the petition said. It identified major stands in the Willamette and Umpqua National Forests in Oregon and the Nez Perce National Forest in Idaho.

Forest Service and timber industry officials said environmentalists were exaggerating the plight of the Pacific yew.

''Its habitat is from Alaska down to Monterrey and east to the Rockies,'' said Barry Polsky, a spokesman for the American Forest Resource Alliance. ''It can hardly from our point of view be considered endangered.''

Len Carey, a spokesman for the Forest Service, said the government is trying to encourage harvesting of the yew for its medical value in connection with logging in national forests.

''We recognize the major importance of taxol and we're trying to manage the national forests to provide a sustainable supply,'' he said.

Jackie Lang, who described herself as a timber community activist from Salem, Ore., broke into tears at the environmentalists' news conference as she accused the speakers of not caring about timber workers' jobs.

''Their real agenda is to shut the forest down. That shuts the communities down,'' she said. Ms. Lang said the old-growth forest currently protected in wilderness areas was enough to protect any endangered species.

Equally emotional was one of McGuire's patients, Marilyn Hoge of Fairfield, Conn., whose case of ovarian cancer was not responding to treatment when she was put on the experimental drug in 1988.

''It was a miracle,'' she told the news conference. ''I never thought I would see my second grandchild and now I have five.''