The Interior Department last month finalized a plan to make the vast majority of an 8.8 million acre portion in the northwest area of the reserve available for drilling.
However, a coalition of green groups -- including the National Audubon Society, The Wilderness Society, Natural Resources Defense Council, Alaska Wilderness League and the Sierra Club - filed a lawsuit in federal district court in Alaska to stop the drilling.
The groups said the administration ignored several federal laws intended to protect key wildlife areas in the reserve for polar bears, caribou, wolves, grizzly bears and migrating birds and it did not adequately study the likely harm that drilling will cause.
\"The administration is really bent over backwards to favor oil development over all other resource values in this area,\" said Deirdre McDonnell, staff attorney for Earthjustice, which is representing the green groups who filed the lawsuit.
The groups also pointed out that nearly 100,000 comments were sent by the public to the Interior Department asking that key wildlife areas in the reserve be protected. Government experts raised similar concerns.
Audubon President John Flicker said the Interior Department\'s plan \"failed to give permanent protection to even one acre of wildlife habitat in the reserve and failed to evaluate any reasonable alternatives that would have done so.\"
However, the department said it will restrict drilling in some areas of the reserve to protect water quality, wetlands, fish and wildlife habitat. Some land use restrictions will also apply to coastal areas, near lakes and along rivers.
Of the 8.8 million acres, leasing will be barred for a decade on 1.57 million acres, or about 17 percent of the area, the department said.
The government estimates the reserve holds between 5.9 billion and 13.2 billion barrels of recoverable oil. The United States consumes about 20 million barrels of crude a day.
The Interior Department plans to lease tracts in the reserve on June 2 to oil companies for exploration.
The 23-million-acre (9.3-million-hectare) National Petroleum Reserve - about the size of the state of Indiana - was created in 1923 to provide a source of energy for the U.S. military. It is located in the northwest corner of Alaska, near the Arctic National Wildlife Refuge, which the Bush administration sought to open to drilling but the U.S. Senate rejected.
Despite sporadic exploration since the 1940s, there has never been commercial oil development in the National Petroleum Reserve.
The Clinton administration opened about 4 million acres in the eastern portion of the reserve to oil drilling after a long industry hiatus in the area. But oil companies were disappointed that certain areas were kept off-limits because of environmental concerns.