MANILA - The Chamber of Mines said Tuesday it filed an opposition against the confirmation of Environment Secretary Gina Lopez, who has led an unprecedented crackdown on alleged unsafe practices in the industry.

Lopez has ordered the closure or suspension of 28 mines and threatened to cancel dozens of permits for upcoming projects.

The group said it concluded that it "will not ever come to a productive and rational dialogue" with Lopez, a known environment advocate before she joined the Cabinet of President Rodrigo Duterte.

"This is the first and only time that the Chamber of Mines of the Philippines has had to resort to this action," the group said.

Lopez had vowed "no cop out" in her campaign to preserve the environment.

"The mining companies accused me of bias, I do. I am really biased on social justice," she said on Tuesday.

"I have a bias for common good. I think it’s healthy for the DENR secretary to have a bias for the common good," she said.

• READ: Lopez 'hopeful' of Duterte support in mining fight