Investigation stepped up after four miners rescued

Authorities have intensified an investigation into a collapse at a gypsum mine in Shandong province after four miners trapped more than 200 meters underground for 36 days were rescued on Friday.

They are also preparing to repair land damaged by gypsum mining.

A team comprising experts and government officials was set up on Saturday to investigate the cause of the accident and to help with the search for those still missing, the local government said.