UPDATE 1-Regulator approves expansion of Antofagasta's Centinela mine in Chile

(Adds CEO comment, details)

SANTIAGO, Dec 12 (Reuters) - Antofagasta Minerals said on Monday that environmental regulators approved a proposed expansion of its Centinela mine in northern Chile, opening the door for a $4.35 billion investment by the Chilean copper mining company.

The expansion project, which is set to be rolled out in two stages, would double Centinela’s copper output to over 400,000 tonnes a year.

“With environmental approval, we will be completing the engineering studies in the coming months,” Antofagasta Chief Executive Ivan Arriagada said in a statement.

“We hope to submit this project to the board of Antofagasta in 2018 once these studies are done. The final authorization to bring this project about will depend on the required investment ... and the possibility of securing financing for its construction, aspects which we are currently working on.”

The expansion would extend the life of the mine to 2056. (Reporting by Gram Slattery; Editing by Meredith Mazzilli and Peter Cooney)