Chilean State miner Codelco halted the operations of three out of four furnaces at its Ventanas copper foundry on Monday morning after high levels of sulphur dioxide were detected, it said in a statement.
Codelco said levels of the gas went 20% over the accepted limit for five minutes, prompting it to shut down the furnaces as a "voluntary and preventative measure" in the industrial area of Ventanas, 90 miles (145 kilometers) northeast of Santiago.
The company's action comes just over a week after more than a hundred local residents sought medical treatment for nausea and vomiting following another gas leak in the same industrial zone.
Amid protests by local residents, the government claimed state-run energy firm ENAP was to blame but the company has denied the claim. Codelco was cleared of any involvement in that leak at another facility.
The State-owned copper miner, the largest in the world, has paid fines for previous excess emissions in area.
It said in its statement that on this occasion there had been no infringement of environmental regulations, while the government confirmed separately that no injury or illness had been reported.
A company spokesman confirmed to Reuters that there would be a "minor impact" on production.