The battle between environmentalists and developers over the US government's decision to list polar bears as an endangered species was reignited this week when the governor of Alaska said she plans to sue the government to block the listing.

Earlier this month, US Interior Secretary Dirk Kempthorne's granted Endangered Species Act protections to the polar bear, making it the first mammal to be listed as threatened as a result of global warming.

Environmentalists welcomed the move as a symbolic victory, providing evidence that the Bush administration is finally beginning to recognise the wide reaching implications of climate change. Although some also criticised the government's decision to insert a caveat in the legislation that stops the listing being used as a means to enact wider carbon regulations and are reported to be currently considering a legal challenge to have the caveat removed.

However, Alaskan Governor Sarah Palin has pre-empted any such move by announcing this week that she would contest the listing, arguing that the designation will slow development in the state and is based on unreliable climate models.

She said that with an estimated 20,000 to 25,000 bears in the Arctic, polar bear populations remain healthy and that further protection is not required. She also warned that while the legislation is unlikely to have a major impact on the activities of oil companies within the state it would hamper a wide range of other development activities.

Steven Daugherty, Alaska's assistant Attorney-General, said that the listing would mean that developers would require reviews and permits for a wide range of activities, describing the process as "basically a big time-and-money waster". He added that the listing was "unwarranted" and that "it is unprecedented to list a currently healthy population based on uncertain climate models".