The directors of two Interior Department agencies said Thursday they're confident oil and gas exploration in the Chukchi Sea off Alaska can proceed without threatening polar bears that depend on the sea ice.

The officials appeared before a House special committee on global warming that is examining why the department is postponing a decision on whether to further protect the bear, at the same time it is proceeding with oil lease sales in the Alaska sea.

Rep. Edward Markey, D-Mass., the committee chairman, asked for assurance that the decision on whether to list the bear under the Endangered Species Act will be made before the Feb. 6 scheduled oil lease sales.

Dale Hall, director of the U.S. Fish and Wildlife Service, who on Jan. 9 postponed the polar bear listing decisions after a year of study, declined to give such assurance.

"It's not just making the decision, it's making it clear and why," said Hall, adding that more time is needed to examine thousands of comments on the issue.

Randall Luthi, director of the Minerals Management Service, which is conducting the oil lease sales, said the bear already is adequately protected against harm from oil and gas development under the Marine Mammal Protection Act. And he said the lease sales include provisions to mitigate the impact on the bear.

"We believe adequate protection exists," said Luthi, nothing that the sea is believed to contain 15 billion barrels of oil and 76 trillion cubic feet of natural gas.

The decision on whether to declare the polar bear threatened under the Endangered Species Act is one of the most complex decisions facing the department. For the first time it links a specific animal's protection with the impacts of global warming. Last September scientific reports provided to Hall's agency concluded that two-thirds of the polar bears would disappear because of shrinking sea ice by mid-century if steps are not taken to curtail global warming.

But Thursday's hearing focused on the potential impact of oil and gas development in the Chukchi Sea on the bear and how it might complicate future protection of the widely revered animal.

If oil and gas development is allowed "we will be accelerating the day when the polar bear will be extinct," said Markey, suggesting that drilling — including the possibility of an oil spill —could be devastating for the bear.

Markey said he was introducing legislation to bar any oil or gas lease sales in the Chukchi off northwestern Alaska until the bear listing is resolved.

Rep. James Sensenbrenner of Wisconsin, the committee's ranking Republican, said while "there may be a problem with the polar bear population" he is convinced that oil and gas development and bear protection can coincide.

"This process is going along fairly well," he said.

Luthi said the agency has reduced the size of the area open for leasing and will have other mitigating requirements to protect the bear.

He said even if the leases are issued before a decision is made on the bear, future listing will have to be taken into account when oil companies seek exploration and development permits.

Rep. Ray Inslee, D-Wash., told Luthi he was not convinced by his assurances. Inslee said his agency's own environmental review of the lease sales concluded a 33 percent to nearly 50 percent chance of a likely oil spill in the Chukchi Sea.

Luthi promised requirements that would reduce those risks.

Dr. Steven Amstrup, a polar bear expert for the U.S. Geological Survey, the Interior Department's science arm, said if there is an oil spill, the impact on bears would be significant.

"The polar bears do not do well when they get into oil," Amstrup told the committee. If bears in the wild get in contact with oil it's likely to be fatal, he said.