US President George W Bush has lifted a ban on oil and gas drilling in an Alaskan Bay known for its wildlife.
The US argues the area would help its energy security
Before any drilling, there will be scope for studies and public comment said the Interior Department, which stressed the need for energy security.
Home to endangered whales, the Bristol Bay is thought to contain some 200 million barrels of oil.
The news comes as a trans-Alaska pipeline was shut down after some 500 gallons of crude oil were spilled.
The spill came from a section above ground in the Brooks Range in northern Alaska, due to a faulty weld, and it remains unknown how long the shutdown will last.
By lifting the ban in the Bristol Bay, some 5.6 million acres (2.3 million hectares) of land will be open for assessment by the Interior Department.
As well as oil, the bay is said to house some 5 trillion cubic feet of natural gas under, somewhere between three and twenty miles from shore.
Moves in the past to drill the area have been met with anger from environmentalists as well as the local fishing community, for whom the bay has a significant interest.
"The president has opened the door for us," said Stanley Mack, mayor of the Aleutians East Borough.
"We're going to walk through it very cautiously," he added.
The important role of fishing - including salmon and red king crab - led Congress to prevent the area from being drilled following a huge oil spill by the Exxon Valdez tanker in 1989.
Exxon is not the only firm to have spilled oil in Alaska.
BP had to close part of its Prudhoe Bay field in Alaska in March 2006 after 200,000 gallons leaked from corroded pipes, prompting severe criticism for the firm's poor maintenance standards.