The panel is reviewing the company's revised environmental impact statement, the second attempt Taseko has made to win approval for the mine.
The federal government rejected the first bid because of fears over its environmental effects, even through the provincial government had backed the project.
The panel says the latest submission from Taseko failed to provide enough information on issues ranging from the project's effects on the environment and wildlife to the food local residents eat, and it's sent the company a long list of questions to answer.
The gold-and-copper mine would be located 125 kilometres southwest of Williams Lake but has stirred strong opposition from First Nations.
Chief Joe Alphonse of the Tsilhqot’in (sill-ko-teen) National Government says Taesko has refused to conduct even the basic studies required to back up claims it can handle the environmental fallout of the mine, and it's making a mockery of the process.