MEXICO CITY (AP) — Environmental authorities filed a criminal complaint Monday against a copper mine that spilled 10 million gallons (40,000 cubic meters) of acids into two rivers that supply water to tens of thousands of people in northern Mexico.

The Attorney General for Environmental Protection said in a statement that it filed the complaint against the Buena Vista del Cobre mining company, which runs the Grupo Mexico-owned mine in Sonora state.

The office said it has also ordered an inspection of all Buena Vista del Cobre’s properties to verify the company is complying with environmental laws.

Authorities have said the spill near the U.S. border was caused by defects in newly constructed leaching ponds, which hold the overflow of acids used to separate metal from crushed rock.

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