Chile's Codelco, the world's top copper producer, suspended operations at its El Teniente and Andina mines after a powerful quake hit Chile on Saturday, a company spokesman said.
The mines sustained power outages after the quake, but there was no serious damage and the spokesman said Codelco expected the mines to be up and running in the coming hours.
However, Mining Minister Santiago Gonzalez told reporters it could take up to two days for production to be resumed at the two mines.
El Teniente and Andina are Codelco's second- and third-largest mines by production, with combined annual output last year of 614,000 tons. The rest of the state miners' operations were not affected by the quake, the spokesman said.
Gonzalez added that the Bio Bio oil refinery, run by state energy company ENAP, had been more seriously affected.
Bio Bio is the biggest of ENAP's three oil refineries and has a refining capacity of 116,000 barrels per day.
(Reporting by Alonso Soto and Fabian Cambero; Writing by Helen Popper; Editing by Vicki Allen)