The company behind one of Minnesota's proposed copper-nickel mines fired back at the federal government Monday with a lawsuit saying regulators have no right to revoke its access to ore deposits next to the Boundary Waters Canoe Area Wilderness (BWCA).

The federal government is considering whether to renew mineral leases held by Twin Metals Minnesota, which are critical for a fiercely contested proposed mine in the Superior National Forest on the edge of the BWCA. In February, the U.S. Bureau of Land Management (BLM) announced it would not automatically renew the leases as it has before — a step that echoed environmental concerns expressed by Gov. Mark Dayton.

Denying them would likely prove fatal to the $2.8 billion mining project.

Now, even before a final decision by the agency, Twin Metals is challenging the federal government's authority to terminate the leases. In a statement released Monday, Twin Metals, a subsidiary of the international mining conglomerate Antofagasta PLC, said, "An essential component of Twin Metals' mineral rights is its entitlement to non-discretionary renewal of these leases. The government has long recognized this renewal right."

Casting a cloud of uncertainty over the project "makes it impossible for Twin Metals to engage in any long-term planning, investment, development, and operational decisions, effectively thwarting any development of the mineral estate; materially harming the future mining project; and jeopardizing Twin Metals' $400 million investment to date," the company said.

Moreover, the company said, the federal government's action "appears to be motivated by political pressure and unsupported allegations about potential impacts of future mining development in the region."

A spokeswoman for the U.S. Forest Service, which shares oversight of the mineral leases, said the agency could not comment on the lawsuit.

Becky Rom, head of a conservation group called the Campaign to Save the Boundary Waters, said there is no question that the federal agencies have the legal right to decide on the leases.

"[Their] authority to renew or deny renewal based on science and proximity to the Boundary Waters Canoe Area Wilderness is absolutely clear," she said.

Other advocates said it's appropriate for the federal agencies to consider the public interest in the matter and the public's views on mining near the BWCA.

"The BLM and U.S. Forest Service have heard from thousands of people that [copper] mining on the edge of the wilderness is an unacceptable risk," said Paul Danicic, executive director of Friends of the Boundary Waters Wilderness.

But copper-nickel exploration, a new kind of mining, is seen by many as a way to save communities on the Iron Range that have been devastated by a slumping world market for iron ore and massive layoffs. They argue that Twin Metals should be allowed to proceed with its exploration and present a plan for mining that would get the same kind of environmental review as other projects.

The mineral leases, which Twin Metals acquired from other mining companies that explored the area, have been in place since the mid-1960s, long before current federal environmental laws took effect. They've been renewed twice without additional environmental reviews or public hearings..

But last February, Dayton came down on the side of environmentalists when he announced that he would not grant the company access to state lands for its project because he had "grave concerns" about the potential impact on the state's crown jewel, the BWCA.

Unlike taconite production, copper mining produces waste rock that can create an acid that leaches heavy metals and other pollutants from rock, a major risk in an area known for its many lakes, rivers and wetlands.

Within days of Dayton's decision, the BLM announced that, according to a federal legal review, it had the option to deny the leases, and asked the U.S. Forest Service to weigh in on whether mining is in the best interest of the Superior National Forest. The Forest Service said it had "deep concerns" about mining in the region, and took the unusual step of holding hearings in June and July to gather public comment on the difficult economic and environmental questions. It is expected to announce the results of that review in coming months, and the BLM will decide whether to renew the leases.

Twin Metals' project is one of two proposed copper-nickel mines under review for northeast Minnesota. PolyMet Mining Corp. has completed an environmental review and is applying for permits for an open pit mine about 20 miles to the southeast of Twin Metals. In contrast to the underground mine proposed by Twin Metals, Polymet's would drain into the St. Louis River watershed and into Lake Superior.

The lawsuit, filed in the U.S. District Court of Minnesota, names as defendants the Bureau of Land Management, the Department of the Interior and its Secretary Sally Jewell and Solicitor Hilary Tompkins.