Mirtha Vasquez said four mines would not be allowed any extensions on their operational timelines.

The San Jose mine, located in Oaxaca, was Mexico’s seventh-biggest silver producer last year.

Global silver demand will rise to 1.029 billion ounces this year.

Assays included 8 metres grading 2.16 g/t gold, including 1 metre at 14.8 g/t gold.

Benchmark has plans to complete the Lawyers feasibility study next year.

The region has good infrastructure, an established regulatory and permitting regime and prospective geological terrain.

The possible shutdown is part of a prolonged fight over the project that could chill investor appetite in Mexico, the world's biggest silver producer.

A recent feasibility study details a further two years at the producing oxide phase and a 10.5-year expansion.