President Barack Obama declared Alaska's ecologically rich Bristol Bay off-limits for oil and gas exploration on Tuesday, saying the move was necessary to safeguard the region's fishing and tourism industries.

The area was being withdrawn from consideration for all future oil and gas leasing, extending indefinitely a temporary ban issued by Obama in 2010, a White House statement said.

"I took action to make sure that one of America's greatest natural resources and a massive economic engine for not only Alaska but for America, Bristol Bay, is preserved for future generations," Obama said in a video.

"It is something that is too precious for us to put out to the highest bidder."

The decision protects millions of acres of pristine coastline and terrain from drilling.

The administration of former president George W. Bush had originally planned a lease sale for the area in 2011.

Bristol Bay forms part of one of the world's most valuable fisheries, helping to provide 40 percent of America's wild-caught seafood and supporting a $2 billion annual fishing industry, the White House said.

The area also generates around $100 million each year from tourism and recreational fishing.

It is home to the world's largest runs of wild sockeye salmon while also providing a haven for many species including the threatened Steller's eider, sea otters, seals, walruses, Beluga and Killer whales, and the endangered North Pacific Right Whale.