MINNEAPOLIS — An environmental group has sued the U.S. Fish and Wildlife Service to preserve federal protections for gray wolves and force the agency to develop a national recovery plan for the species.

The Center for Biological Diversity filed the lawsuit in federal court in Washington, D.C., Wednesday, a day after the service denied the group's petition for a nationwide recovery plan. The service said its regional approach meets the legal requirements.

But the group says the agency is required under the Endangered Species act to foster the recovery of gray wolf populations across their former range, not just in the northern Rockies, the Great Lakes region and the southwest.

Congress lifted federal protections for northern Rockies wolves, but courts have blocked efforts to lift them in Minnesota, Wisconsin and Michigan.

The Department of Justice says it's reviewing the complaint and has no further comment.