A Canadian-owned mine in northern Mexico spilled nearly 1.9 million litres of a cyanide solution used in heap-leach gold mining, after heavy rains caused a retaining pond to overflow.
The accident occurred at the Proyecto Magistral mine in the northern state of Durango. The mine is owned by a subsidiary of Toronto, Canada-based McEwen Mining Inc.
The Attorney General for Environmental Protection said Wednesday that the cyanide-laced solution contaminated an area of about a half-kilometre.
The office ordered the company to install membranes in holding ponds and raise the height of containment dams.
It was the second mine spill in as many weeks in Mexico. Earlier this month, a mine in Sonora state spilled 40,000 cubic metres of mining acids into a river.