WASHINGTON, Dec. 28 (UPI) -- By the end of 2007 Polar bears may be listed as a threatened species under the U.S. Endangered Species Act, because their habitat is disappearing.

"Polar bears are one of nature's ultimate survivors, able to live and thrive in one of the world's harshest environments," said Secretary of the Interior Dirk Kempthorne. "But we are concerned the polar bears' habitat may literally be melting."

The Department of the Interior is conducting a further 12-month study that will include a public comment period, before making a final decision on the polar bear's status, CNN reported Thursday.

The announcement comes after three conservation groups filed a lawsuit against the Department of the Interior, in an effort to protect the polar bear from the effects of global warming.

"The science is extraordinarily clear: Global warming in the Arctic threatens polar bears," said Kassie Siegel, an attorney with the Center for Biological Diversity.