Lopez asked Semirara to explain why its environment compliance certificate (ECC) should not be revoked. The company said it had not received a copy of the order.
Semirara shares were down 5.95 percent to P109 after Lopez's announcement.
"But we would like to reiterate that Semirara Mining and Power Corporation has been fully complying with all relevant laws and regulations," the company said in a statement.
"Our mining and environmental protocols also conform with the conditions of our ECCs. We hope that our company will be accorded due process throughout any pre- and formal audit process of the government," it added.
