Conservation groups based in Alaska have accused the Obama administration of repeating the mistakes of George Bush after it gave the conditional go-ahead for Shell to begin drilling offshore for oil and natural gas in the environmentally sensitive Beaufort Sea.

The Minerals Management Service, part of the federal Interior Department, yesterday gave Shell the green light to begin exploratory wells off the north coast of Alaska in an Arctic area that is home to large numbers of endangered bowhead whales and polar bears, as well as walruses, ice seals and other species. The permission would run from July to October next year, though Shell has promised to suspend operations from its drill ship from late August when local Inuit people embark on subsistence hunting.

Environmentalists condemned the decision to allow drilling, saying it would generate industrial levels of noise in the water and pollute both the air and surrounding water. Rebecca Noblin, an Alaskan specialist with the conservation group the Centre for Biological Diversity, said: "We're disappointed to see the Obama administration taking decisions that will threaten the Arctic. It might as well have been the Bush administration."

Whit Sheard, the Alaskan expert with the environmental group Pacific Environment, accused the US Interior Department of "again trying to implement an overly aggressive Bush-era drilling plan in one of the riskiest areas on the planet to drill".

The question of offshore oil drilling in the Arctic was one of the controversial environmental issues that confronted the Bush administration. Its permission for exploration in the Beaufort Sea, widely condemned by environmentalists, was struck down last year by a federal court on grounds that it had failed sufficiently to consider the impacts on bowhead whales and the subsistence activities of Inuit populations.

The ruling was later set aside and Shell withdrew its drilling plans.

According to the National Marine Fisheries Service, there are between 30,000 and 50,0000 bowhead whales in the world, with up to 9,000 of them feeding in the Beaufort Sea. The whales migrate twice a year through the area and are crucial to the subsistence economy of the Inupiat people.

Whale experts warn that the bowhead stocks are sensitive to noise and could be driven further off shore by the disruption of drilling. That in turn would have an impact on their chances of survival, which have already been harmed by early side-effects of global warming.

There are also fears that any drilling could lead to oil spills which would be impossible to clean up amid the Arctic's broken sea ice.

Shell must now satisfy the authorities that it has met air and water quality standards and safeguards for whale protection before it can begin drilling. The oil company's head in Alaska, Pete Slaiby, said objections had been taken into account.

"We sincerely believe this exploration plan addresses concerns we have heard in the North Slope communities which have resulted in the programmes being adjusted accordingly," he said.