The government agency also said the area could contain 1,670 trillion cubic feet (Tcf) of natural gas.

"Before we can make decisions about our future use of oil and gas and related decisions about protecting endangered species, native communities and the health of our planet, we need to know what's out there," said USGS Director Mark Myers.

"With this assessment, we're providing the same information to everyone in the world so that the global community can make those difficult decisions," he said.

Frank O'Donnell, president of the nonprofit group Clean Air Watch, said not only do polar bears and other wildlife within the Arctic Circle face losing their habitat due to global warming, they would be hurt by companies searching for oil.

"On the one hand you may see this region more accessible (for getting energy supplies), but we're definitely going to pay a different kind of price...you may loose species," O'Donnell said. "The oil industry goes up there and industrializes what has been a pristine area...suddenly it becomes the new Houston."

The 90 billion barrels of oil expected to be in the Arctic could meet current world oil demand of 86.4 million barrels a day for almost three years.

But the Arctic's oil is not intended to replace all the supplies in the rest of world. It would last much longer by boosting available supplies and possibly reducing US reliance on imported crude in the future, if America developed the resources.

The Arctic accounts for about 13 percent of the world's undiscovered oil, 30 percent of the undiscovered natural gas and 20 percent of the undiscovered natural gas liquids, the agency said in the first publicly available petroleum resource estimate of the entire area north of the Arctic Circle.

More than half of the undiscovered oil resources are estimated to occur in just three geologic provinces: Arctic Alaska (30 billion barrels), the Amerasia Basin (9.7 billion barrels) and the East Greenland Rift Basins (8.9 billion barrels).

More than 70 percent of the undiscovered natural gas is likely to be in three provinces: the West Siberian Basin (651 Tcf), the East Barents Basins (318 Tcf) and Arctic Alaska (221 Tcf), the USGS said.

Technically recoverable resources are those energy supplies that can be put into the market using currently available technology and industry practices.

The USGS said it did not consider economic factors, such as the effects of permanent sea ice or water depths, in its assessment of undiscovered oil and gas resources.

Energy companies have already found more than 400 oil and gas fields north of the Arctic Circle.

The discovered fields account for approximately 40 billion barrels of oil, more than 1,100 Tcf of gas and 8.5 billion barrels of natural gas liquids.

"Nevertheless, the Arctic, especially offshore, is essentially unexplored with respect to petroleum," the USGS said. (Editing by David Gregorio)