The Interior Department will announce Thursday that is it postponing oil drilling in the Arctic until at least 2011 amid widening fears that an oil spill there could be many times worse than the blowout in the Gulf of Mexico.

The decision by Secretary Ken Salazar will halt permit approvals for new exploratory drilling this summer in the Beaufort and Chukchi seas so that additional information can be gathered on proposed drilling technology and to evaluate what capability exists to respond to an oil spill in often ice-laden Arctic waters.

The postponement is included in a broader Interior Department report that that will be released Thursday detailing new regulations and policies on oil drilling.

An administration official, speaking on condition of anonymity because the announcement had not yet been made, said the decision is consistent with the White House’s desire to take a “cautious, science-based approach” for determining which areas of the Outer Continental Shelf off Alaska may be appropriate for oil production.

The decision directly affects Shell Oil Co., which had all-but-final authorization to drill five new exploratory wells in the Beaufort and Chukchi seas, three of which it had planned to begin this summer.

Salazar this year cancelled four additional lease sales, which had been scheduled in the 2007-12 offshore leasing program. The move was to allow officials to determine the potential effects of oil drilling on the fragile Arctic environment, which is the only remaining habitat for threatened polar bears, endangered bowhead whales and many other species.

“Secretary Salazar determined that the country must take a cautious approach in the Arctic, and gather additional scientific information about resources, risks and environmental sensitivities before making decisions about potential future lease sales,” the official said.

Many of the nation’s biggest environmental organizations and many Alaska Natives, who survive by hunting and fishing along the Arctic coast, have demanded a suspension of new drilling in the Arctic.

“It is with heavy hearts that we look upon the Gulf of Mexico spill as a reminder of the risks involved in exploratory drilling in our oceans,” the Inupiat Community of the Arctic Slope, which represents 9,000 native residents of Alaska’s North Slope, said in a recent letter to Salazar.

“As the country scrambles to clean up the disaster in the Gulf of Mexico, Shell Oil is getting ready to drill exploratory wells in the Arctic Ocean, one of the most remote and extreme environments on Earth,” the letter said. “The Arctic coast does not have the infrastructure in place, nor is there technology available, to respond effectively to a blowout or oil spill offshore.”

As was the case with the BP exploratory rig that exploded in the gulf, the federal Minerals Management Service in Alaska concluded that there was no need to conduct a full environmental impact report for Shell’s proposed drilling in the Arctic. Federal officials concluded the chances of such a spill were too remote.

Yet in its findings, the agency ignored several concerns raised by government scientists, among them that an oil spill could have devastating consequences for polar bears.

Meanwhile, the Trans-Alaska Pipeline, which transports oil from the North Slope to tankers 800 miles away in Valdez, remained shut down for a second day Wednesday after thousands of gallons of crude spilled into a containment area as a result of a power failure during scheduled testing at a pump station in central Alaska.

jtankersley@latimes.com

kim.murphy@latimes.com

Murphy reported from Seattle and Tankersley from Washington.