The Interior Department yesterday formally identified the northern spotted owl as a threatened species, but specific steps to protect the owl were held up by White House concerns that they will harm the timber industry in the Pacific Northwest.

The announcement by U.S. Fish and Wildlife Service Director John F. Turner marks the government's acknowledgment that logging in the ancient coniferous forests that are the owl's natural habitat has driven the bird perilously close to extinction. But it also poses a quandary for an administration that has pledged to be environmentally sensitive while at the same time safeguarding jobs and economic growth.

White House officials are particularly opposed to a proposal by the U.S. Forest Service to set aside large areas of forest for the owl, which would reduce the timber harvest and eliminate 28,000 jobs, by some estimates.

"Our intent now . . . is to find ways to protect the owl with the least possible disruption to the timber economy of the Northwest," said Turner.

"The biological evidence says the northern spotted owl is in trouble. We will not and, by law, cannot, ignore that evidence. . . . But I strongly believe there is room in the world to protect both owls and loggers."

The fate of the 2,000 pairs of spotted owls that remain in the Northwest has become the focal point of a larger battle over the future of so-called old-growth forests, 300- to 700-year-old stands of spruce and Douglas fir found mostly on the western slope of the Cascades in Oregon and Washington.

Once these forests covered an estimated 25 million acres. Logging has destroyed all but 2.3 million acres, and less than half that total is protected in national parks and wilderness areas, according to the Wilderness Society, a conservation group whose estimates are accepted by the Forest Service as generally accurate.

The remainder, about 1.2 million acres, will be completely logged in the next 15 to 20 years if cutting continues at present levels, according to the Wilderness Society.

The spotted owl is one of about 100 species whose survival is linked to old-growth forests. Conservationists consider it an "indicator" species whose decline reflects the poor health of an ecosystem that is still only dimly understood. They are pressing for legislation that would set aside much of the remaining forest in permanent nature preserves.

"The owl's listing is proof of how human greed has driven yet another species dangerously close to extinction," said Jay D. Hair, the president of the National Wildlife Federation. "At least now the nation has a chance to do the right thing for the owl and for our national treasure, the ancient forests."

The timber industry yesterday disputed the scientific justification for listing the owl as a threatened species, and warned that the decision could cost more than 50,000 jobs. "It's time for economic reality and the needs of the people to come to bat," said Mark Rey, executive director of the Northwest Forest Resource Alliance.

Turner described his decision to list the owl, which takes effect July 23, as "difficult and painful," recalling his previous position as a Wyoming state legislator at a time of economic decline. The listing triggers a legal process that will result in an interim protection plan, to be followed within a year by a full-scale plan for the bird's recovery.

But the shape of those plans was very much in doubt yesterday. Interior officials originally had scheduled a news conference to announce both the listing and the short-term protection plan, but scaled back the event after the White House and the various agencies involved failed to reach agreement on its details.

White House officials, led by domestic policy adviser Roger Porter, have objected to a Forest Service plan that would adopt the recommendations of an interagency scientific panel convened to draft a strategy for saving the owl, sources said. The panel recommended setting aside large "habitat conservation areas," a step the service has estimated would cost 28,000 jobs when combined with other owl protection measures already in the works.

"We're getting a lot of heat from the White House . . . as to why we haven't come up with something that provides more timber," said a Forest Service official who asked not to be identified. "Believe me, we've tipped the world upside down looking for something that would provide more timber and protect the owl."

White House spokesman Stephen T. Hart said the decision on the owl protection plan was being left to the agencies, but he added, "George Bush is concerned about the potential loss of jobs, yes, and he has expressed his hope that we can strike a balance."

An administration official involved in the discussions said that senior White House officials are concerned not only about the owl protection plan but about "the rigidity" of the Endangered Species Act itself. The official repeated the administration's public statement that there are "no plans" to call for an overhaul of the act, but said there "is virtually no disagreement here that the law does not reflect the kind of balance the president would like to see."

An alternative to the Forest Service plan has been proposed by Interior's Bureau of Land Management, which manages about 10 percent of the old-growth forests in the Northwest. BLM has proposed a variety of artificial measures aimed at supporting the birds in smaller areas of old-growth, including feeding the birds, transplanting owl eggs and "artificial nest structures."