Several Chilean cities were engulfed by days of riots, along with peaceful protests, after a hike in public transport costs. Arson, looting and riots over the weekend left at least seven dead.

"This strike is a warning," said Patricio Tapia, president of Escondida's Union #1. He said workers would walk off for "at least one shift tomorrow."

Mining minister Baldo Prokurica told Reuters late on Sunday that the country's mines operated normally through the weekend.

Escondida is the world's largest copper mine.

(Reporting by Fabian Cambero; Writing by Dave Sherwood; Editing by Alison Williams and Nick Zieminski)