Production at four copper mines were halted by a 8.8-magnitude megaquake, which hit Chile on Saturday and so far has killed over 300 people.

The state-run Codelco suspended production at the El Teniente mine, 80 km south of Santiago, and the Andina mine, 80 km northeast of Santiago. But the world's largest copper producer said it expected them to resume operations quickly.

The massive quake also forced the Anglo American Plc mining company to halt production at the Los Bronces mine, 65 northeast of Santiago, and the El Soldado mine, 132 km north of Santiago. Other major mines were operating normally.

Chile, the world's largest copper supplier, produced 5.41 million tons of copper in 2009.

More than 300 people have been killed after the quake, one of the world's most powerful in decades, rocked central Chile at 3:34 a.m. local time (0634 GMT) on Saturday, the national emergency office said.

The epicenter was only 115 km from Concepcion, Chile's second largest city with a population of 670,000.

Chilean President Michelle Bachelet has declared a "state of catastrophe" in central Chile and called on residents in the affected areas to remain calm.