As lawsuits over the BP oil spill mount, a group of conservationists and fishermen have a new target: the Department of Interior’s Minerals Management Service.

Earthjustice, an environmental law firm, and New Orleans’ Waltzer & Wiygul filed suit in federal court on Tuesday against the federal agency. The suit — Gulf Restoration Network and Sierra Club v. Salazar (pdf) — charges that the agency violated federal law by exempting oil companies that drill in the Gulf of Mexico from disclosing blowout and worst case spill scenarios as well as plans for dealing with them before approving the companies’ offshore drilling plans.