CHEYENNE, Wyo. (AP) — A Navajo Nation company may continue operating a coal mine for two more months amid ongoing negotiations over the terms of a state permit, Montana officials announced Tuesday in granting an extension that keeps about 300 miners at work.

The Montana Department of Environmental Quality and the Navajo Transitional Energy Company have been negotiating how the department might be able to take the company to court over any potential environmental violations at the Spring Creek mine near Decker, Montana.

Without a waiver of immunity, the state might not be able to successfully sue the tribe as a sovereign nation.

The two sides have agreed to a 65-day extension of an earlier interim waiver of sovereign immunity, department officials announced.

The company acquired Spring Creek, and the Antelope and Cordero Rojo mines in Wyoming, from Gillette-based Cloud Peak Energy in a 2019 bankruptcy sale. The purchase made the Navajo Transitional Energy Company the third-biggest U.S. coal company.

Eagle Butte closed for two days in late October after Montana officials refused to issue the company an operator permit, putting about 300 miners — most from nearby Wyoming — temporarily out of work. The department and company agreed to an interim waiver of sovereign immunity while they negotiated the permit terms.

The interim waiver was set to expire Wednesday. The extension will keep the mine from closing again while the two sides keep negotiating.