An environmental group is threatening to sue the U.S. government for failing to draw up a plan to protect two coral species newly listed as endangered.

The Center for Biological Diversity in Tucson, Ariz., helped get elkhorn and staghorn coral their status, The Palm Beach Post reported. Under the Endangered Species Act, the National Marine Fisheries Service had a one-year deadline, which expired this week, to draw up a protection plan.

"One of the reasons that the Endangered Species Act has very strict deadlines is that while a species is waiting to be protected, they could go extinct," said Miyoko Sakashita, a attorney for the center.

Sakashita said the two species are threatened by global warming and by pollution in coastal waters.

Copyright 2007 by United Press International