MINNEAPOLIS (AP) — Several environmental groups and a Native American tribe have gone to court to challenge a permit issued by the Army Corps of Engineers for the planned PolyMet copper-nickel mine in Minnesota.

The lawsuits filed in federal court Tuesday say the corps violated federal law when it issued a permit authorizing the destruction of wetlands for the project. It was the final permit PolyMet needed, and requires steps to mitigate the impact.

The lawsuits are the latest among several pending challenges to the project. One comes from Friends of the Boundary Waters Wilderness, the Minnesota Center for Environmental Advocacy, the Center for Biological Diversity and Earthjustice. The other comes from the Fond du Lac Band of Ojibwe.

PolyMet says it's confident the agency's approvals were fully consistent with all applicable laws.

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