Cities across Chile were without power on Sunday and output at some mines disrupted after a main power grid failed a fortnight after a massive earthquake killed hundreds and ravaged infrastructure.
State mining giant Codelco, the world's top copper producer, said the disruption shut its mines in central Chile. But its Codelco Norte division in the northern part of the country was unaffected.
Global miner BHP Billiton's Escondida deposit, the world's largest copper mine, was operating normally and was not affected, a union leader said.
Most of Chile's copper mines are on the northern power grid, which was not hit by the blackout on the central grid.
Presidency Minister Cristian Larroulet said power could return in the coming hours.
The blackout began at 8:50 p.m. (2350 GMT) and affected the capital, Santiago, as well as cities such as Concepcion, which was recently devastated by a major earthquake.
Interior Minister Rodrigo Hinzpeter told local media the blackout was due to a problem with a-500 kilowatt transformer.
He said that while the power outage was not directly related to an 8.8-magnitude earthquake that struck Chile on February 27, there would be an investigation to see whether there was an indirect cause.
He said it was not clear how long it would take for the power supply to fully recover. Power was slowly coming back to some parts of Santiago, but many other cities were still in darkness. Phone service was also down in much of the country, witnesses said.
The Central Interconnected System, or SIC grid, was the one affected. It delivers power to many cities in the country including the capital.
"We've stopped receiving energy in the Santiago distribution grid," Juan Pablo Larrain, spokesman Chilectra power company told Chile's TVN television.