HELENA, Mont. -

A wildlife advocacy group is suing the U.S. Forest Service for the release of documents that discuss the agency's plans to keep a disease that has already killed millions of bats in the U.S. and Canada from spreading to the Northern Rocky Mountains.

The Center For Biological Diversity filed its lawsuit Wednesday after the Forest Service withheld 13 pages of records from the advocacy group's Freedom of Information Act request.

Center spokeswoman Mollie Matteson says the documents may explain why the agency has not taken any action to prevent the spread of white-nose syndrome to Montana, Idaho and parts of Washington, North Dakota and South Dakota.

Forest Service officials say they can't comment on the lawsuit. But agency spokesman Phil Sammon says several preventative measures are pending final approval.