WASHINGTON, March 6 (Xinhua) -- The U.S. Fish and Wildlife Service may soon begin the process of lifting gray wolves from the endangered species protection list, a move that will likely draw controversy.

Speaking at a conference in Denver, acting Interior Secretary David Bernhardt said recovery of the gray wolf population has been a "great conservation success."

In a statement to the press, the Fish and Wildlife Service said it will "soon propose a rule to delist the gray wolf in the lower 48 states and return management of the species to the states and tribes."

The statement did not detail a time frame for the process.

Gray wolves are currently protected in all U.S. states except Alaska and Hawaii, meaning that they cannot be hunted or killed, except under special circumstances.

The population of gray wolves in the lower 48 states dropped to around 1,000 in the 1970s, when the species was put on the protection list. Now the population has recovered to more than 5,000.

State lawmakers have long wanted the federal government to hand back the right to regulate gray wolves. Wisconsin state Senator Tom Tiffany hailed Bernhardt's announcement, saying his state should be in charge of wildlife management, especially after the wolf population increase has led to frustrations among farmers and hunters.

But environmental conservationists are skeptical of the move, saying the wolf population still cannot sustain hunting and killing.

"This disgusting proposal would be a death sentence for gray wolves across the country," Collette Adkins, a senior attorney at the Center for Biological Diversity, said in a statement.

Gray wolves primarily roam the northern part the contiguous United States, and is a keystone predator and an integral component of the ecosystems to which it typically belongs.