The state of Alaska has filed a lawsuit against the U.S. government, in an attempt to overturn the listing of polar bears as a threatened species.

The lawsuit was filed Monday with the U.S. District Court in Washington, D.C., Alaska Gov. Sarah Palin announced in a release that day.

It comes two months after Alaska asked U.S. Interior Secretary Dirk Kempthorne and the U.S. Fish and Wildlife Service to downgrade polar bears' risk status.

Kempthorne declared polar bears to be threatened on May 14, saying the animals' sea ice habitat has dramatically melted and computer models suggest the trend will continue.

But Palin stated the federal analysis "was not based on the best scientific and commercial data available," arguing that it did not adequately consider polar bear survival through earlier periods of warming.

She also said existing regulatory mechanisms in Alaska and elsewhere in the world have led to a sustainable worldwide polar bear population.

The polar bear is listed as a species "of special concern" in Canada, which is one step down from "threatened" and two steps down from "endangered."

In April, the scientific committee that advises the Canadian government on species at risk recommended that the polar bear's status remain unchanged. The federal cabinet makes the final decision on what species should be listed under the Species at Risk Act.

The committee's recommendations are expected to be forwarded this month to Environment Minister John Baird, who has said he would review the findings before commenting on how the government would respond.

Environmental activists and polar bear experts said they wanted the more serious "threatened" status in Canada, especially in light of the U.S. assessment.

With files from the Associated Press