US President Barack Obama said Sunday he would recommend a large swath of Alaska be designated as wilderness, the highest level of federal protection, in a move angering state oil proponents.

By setting aside 12.28 million acres (five million hectares) of public land in the Arctic National Wildlife Refuge, or ANWR, as wilderness, the oil-rich area would be sealed off from roads and development, including drilling.

"I'm going to be calling on Congress to make sure they take it one step forward, designating it as a wilderness so we can make sure that this amazing wonder is preserved for future generations," Obama said in a video posted online.

If Congress approves the measure, it would mark the largest wilderness designation since the classification was created more than 50 years ago.

The 19.8-million-acre ANWR is home to countless species, including polar bears, gray wolves, caribou, muskoxen, more than 200 species of birds and 42 species of fish.

"It's very fragile and that's why I'm proud my Department of Interior has put forward a comprehensive plan to make sure we're protecting the refuge, and that we're designating new areas including coastal plains for preservation," Obama said.

More than seven million acres of the refuge are already designated as wilderness, but don't include Alaska's coastal plain, which is home to numerous species and oil.

"Just like Yosemite or the Grand Canyon, the Arctic National Wildlife Refuge is one of our nation's crown jewels and we have an obligation to preserve this spectacular place for generations to come," said Interior Secretary Sally Jewell.

- 'What an awful thing' -

But Alaska Republican Lisa Murkowski, who chairs the Senate Energy and Natural Resources Committee, slammed the move, calling out Jewell and Obama.

"What an awful thing for AK to wake up to on a Sunday: gut punches from this White House to our economy and future," she tweeted, using an abbreviation for the state.

Meanwhile, the committee's Republicans cited a Friday phone conversation between Murkowski and Jewell, in an online post.

"What's coming is a stunning attack on our sovereignty and our ability to develop a strong economy that allows us, our children and our grandchildren to thrive," Murkowski said in a statement.

Alaska Governor Bill Walker derided the move, tweeting that he joined his state's congressional delegation in "denouncing President Obama's attempt to block future oil development in ANWR."

But the White House defended the proposed expansion in a blog post.

"The Obama administration believes that oil and natural gas resources can be developed safely. Unfortunately, accidents and spills can still happen," wrote presidential counselor John Podesta and Mike Boots, head of the White House Council on Environmental Quality.

Environmental groups heralded the move.

"This wilderness recommendation has been a long time coming for the place where life begins for the porcupine caribou herd and for many of America's polar bears," Center for Biological Diversity Alaska director Rebecca Noblin said.

Neither the Interior Department nor Obama referenced oil in their announcements.

The agency also said it was recommending four Alaskan rivers for protection under the National Wild and Scenic Rivers System.