The lawsuit asks that the court prohibit the federal agency from denying mineral exploration permits to Twin Metals.

But the Interior Department attorneys, joining an argument filed by environmental groups earlier this month, said the suit is premature because no decision has been made that can be challenged.

The motion, filed in federal court in the Twin Cities, will have to wait, however. No hearing on the issue is scheduled until April 28.

The U.S. Forest Service is expected to decide soon whether to support or oppose renewing mineral leases to Twin Metals. The agency has said it has grave concerns about the location of the mine on the edge of the Boundary Waters Canoe Area Wilderness. The Interior Department likely will abide by the Forest Service decision.

Twin Metals has said its giant underground copper mine project would be impossible without access to the federal minerals in the area east of Ely.