ANCHORAGE, Alaska - An environmental group on Thursday gave formal notice that it intends to sue the U.S. federal government for its failure to protect polar bear critical habitat from harmful oil and gas development.

The Center for Biological Diversity sent the required notice to Interior Secretary Ken Salazar.

The group's Alaska representative says the Interior Department designated more than 187,000 square miles in and near the Beaufort and Chukchi seas as polar bear critical habitat.

But attorney Rebecca Noblin says agencies also have reaffirmed a Bush-era plan that authorized oil leasing in the newly designated polar bear critical habitat in the Chukchi Sea, and are considering a proposal to allow Shell Oil to drill next summer in polar bear critical habitat in the Beaufort Sea.

Polar bears were declared a threatened species in 2008.