SEATTLE (AP) _ The Bush administration has quietly asserted that it has the power to declare any Indian tribe in the nation extinct, even if the tribe has been recognized by a congressionally ratified treaty.

The new policy is stated deep in the text of a Bureau of Indian Affairs decision last month denying recognition to the Miami tribe of Indiana, the Seattle Post-Intelligencer reported Thursday.

The BIA, an agency of the Interior Department, says it has no plans to use the power to disqualify already-recognized tribes, though it claims the right to do so if they fall short of agency requirements on continuous existence.

Indian law experts say the new policy is an intrusion by the executive branch on Congress' treaty-making powers.

''The BIA can now roam and reconsider the tribal status of any tribe it chooses. It's a shocking conclusion,'' Arlinda Locklear, a lawyer for the Miamis, told the Post-Intelligencer.

At stake is not just the legal status of hundreds of tribes, but their claims to land, benefits and fishing rights and their rights to tax and regulate businesses that operate on their land.

The administration policy statement cites as its legal basis a 1979 decision by the late U.S. District Judge George H. Boldt.

He signed, virtually unchanged, a proposed order written by BIA lawyers that declared extinct five groups of Northwest Indians who never previously were recognized by the government as tribes.

At least one of those groups is seeking to appeal Boldt's decision on grounds that his mind was failing. Boldt suffered from Alzheimer's disease.

Interior Department spokesman Bob Walker acknowledged the Bush administration has asserted its power to declare any tribe extinct.

''That is what the court says, that we have that right,'' he said.

Boldt's ruling didn't concern already recognized tribes.

BIA criteria for defining a tribe include living in a community viewed as American Indian and distinct from other tribes, maintaining tribal influence over members and proving descendancy from a single historical tribe.

John Shappard, a former BIA official who was the main author of the 1978 tribal-acknowledgment rules, said this week he never anticipated the process could be used to eliminate recognized tribes.

''Traditional wisdom has it that only Congress can terminate a tribe,'' Shappard said. ''What is so bothersome about it is the BIA could cut back on its budget by picking off some tribes, just bumping them off. I didn't intend that in the regulations.''