A judge halted a federal lease sale of oil-rich land on Alaska's North Slope that environmentalists have pinpointed as a haven for migratory birds and calving caribou.

The decision Monday in U.S. District Court in Anchorage blocks a lease sale of about 1.7 million acres (0.68 million hectares) that the Bureau of Land Management had planned for Wednesday. The sale would have included the Teshekpuk Lake area, which sits above 2 billion barrels of recoverable oil, federal estimates say.

President Warren Harding set aside the National Petroleum Reserve-Alaska in 1923 in anticipation of the country's energy needs, but since then environmental groups have argued that a 600,000-acre (240,000-hectare) section of the reserve at Teshekpuk Lake contains some of the most important wetlands in the Arctic.

Judge James K. Singleton echoed a decision he had issued on Sept. 7 that temporarily halted the sale. Government environmental studies, Singleton wrote, were too narrow in scope because they did not consider how leasing in the northeastern part of the 23-million acre (9.2 million-hectare) reserve would affect land and wildlife in the northwestern section.

The government is fighting hard to put at least a portion of the leases up for bid.

The Interior Department had offered last week to temporarily abandon the sale of oil leases near the lake, asking the court to allow the leases outside the Teshekpuk region to proceed.

As he did in the ruling earlier this month, Singleton chastised federal and state agencies, and oil companies for violating the National Environmental Protection Act.

He also singled out Interior Secretary Dirk Kempthorne saying that Kempthorne "abused his discretion" by deciding to hold the sale despite an inadequate environmental impact statement.

Plaintiffs, who included the National Audubon Society and the Center for Biological Diversity, called the ruling a victory.

"We believe and hope that when the government takes a full look at the environmental impact to this area, it will come out with a decision that protects the resources better," said Deirdre McDonnell, an attorney for Earthjustice in Juneau.

Nearly 13 million acres (5.2 million hectares) of the reserve are available for lease sale or have been sold to oil companies, most notably ConocoPhillips. The company hopes to augment waning crude stocks in the Prudhoe Bay fields east of the NPR-A.

A call to the company's Anchorage spokeswoman on Monday was not immediately returned.

The reserve contains between 5.9 and 13.2 billion barrels of technically recoverable oil resources, according to federal estimates.