A truck driver who was critically injured in an accident at a giant U.S.-owned mine in Indonesia has died in a hospital.

Mine operator PT Freeport Indonesia says liquid ore material flowed into a truck during maintenance activities on Friday, injuring the Indonesian driver. He died late Saturday.

On May 14, a tunnel inside the Big Gossan facility collapsed, killing 28 of 38 workers who were undergoing safety training in an underground classroom.

The company's president-director, Rozik B. Sutjipto, says Friday's accident was not related to the tunnel collapse and that the cause is under investigation.

The mine, located in Indonesia's easternmost Papua province, is owned by Phoenix, Arizona-based Freeport-McMoRan Copper & Gold Inc.