US environmentalists on Thursday hailed a delay in Royal Dutch Shell's Alaska oil drilling plans as a victory for polar bears, but outraged local leaders said the move would cost jobs.

The Anglo-Dutch oil giant said it has put off plans to drill off Alaska's coast this year after a board of the federal Environmental Protection Agency (EPA) ordered further study on the impact.

"Despite our best efforts, critical permits continue to be delayed, and the timeline for getting these permits is still uncertain," Royal Dutch Shell chief executive Peter Voser said as he discussed the company's financial results.

Royal Dutch Shell, which almost doubled its net profit in 2010, said it would instead aim to start drilling in 2012.

The Sierra Club called the delay "a victory for worker safety and the environment." It voiced fear at how the Arctic Ocean -- which experts say is deeply affected by climate change -- would cope with a BP-style oil spill.

"The Arctic should not be an option for corporate polluters who are already reaping in massive profits," said Athan Manuel, the director of the environmental group's land protection program.

"The cold truth is there is no way to clean up an Arctic spill," he said.

The Center for Biological Diversity called on US authorities to make the delay permanent.

"The polar bear and other wildlife of Alaska's Arctic, as well as the local communities that depend upon a healthy ocean, were granted a well-deserved reprieve," said Brendan Cummings, the group's senior counsel.

But Alaska Governor Sean Parnell, a Republican, accused President Barack Obama's administration of failing to "act on the opportunity for jobs and economic growth."

"This is just another delay resulting from the federal government dragging its feet, killing jobs and making us even more reliant on oil from the Middle East and elsewhere," Parnell said.

Senator Mark Begich, a member of Obama's own Democratic Party, said it was "shameful to see another season lost" as he pointed to the billions of dollars already invested in the project.

"I put the blame for this squarely on the EPA and the Obama administration who have taken virtually every opportunity to block responsible development of Alaska's resources," he said.