Opponents of plans to extract oil from along southern Montana's Beartooth mountain range have sued a state oversight board that approved an initial drilling permit.
The Northern Plains Resource Council and affiliated Carbon County Resource Council filed the lawsuit Wednesday in state district court in Yellowstone County.
They want a judge to void the drilling permit awarded to Denver-based Energy Corporation of America.
The groups say the state Board of Oil and Gas Conservation violated public participation requirements when it canceled a scheduled public hearing on the company's proposal last month due to a technicality.
Energy Corporation of America last year announced plans to develop dozens of wells near Roscoe and along the Clarks Fork of the Yellowstone River. Drilling opponents say thousands more wells could follow.