An Alaska tribe and five environmental groups say the federal government performed inadequate environmental review before approving petroleum exploration in a reserve.
The Native Village of Nuiqsut and the groups on Thursday sued the Bureau of Land Management.
They say the agency did not consider direct and cumulative effects of exploration in the National Petroleum Reserve-Alaska on caribou, migratory birds and other wildlife.
The BLM in December approved winter exploration by ConocoPhillips Alaska.
The agency and the company on Friday declined comment on the lawsuit.
Nuiqsut is on the east border of the reserve on Alaska's North Slope. Villagers hunt caribou that live there year-round.
Tribal administrator Martha Itta says effects of oil development are not well understood and BLM needs to take time to understand impacts.