Associated Press - November 20, 2009 3:34 PM ET

ALBUQUERQUE, N.M. (AP) - An environmental group is threatening to sue the U.S. Fish and Wildlife Service over its failure to respond to a petition involving the Mexican gray wolf.

The Center for Biological Diversity had filed a petition asking the agency to list the wolf on the endangered species list separate from other gray wolves in North America or as a distinct population.

The group says wolf recovery in New Mexico and Arizona has fallen off the tracks partly because of the legal limbo the animal faces as a subspecies of the gray wolf.

The Mexican wolf was exterminated in the wild in the Southwest by the 1930s. First listed as endangered as an individual species in 1976, the Fish and Wildlife Service created a species-wide designation for gray wolves in 1978.

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