Emergency crews are struggling to rescue 18 coal miners trapped underground in eastern China following a collapse three days earlier.

Three miners were killed by falling rocks in Shandong province in the incident on Saturday which also destroyed part of a drainage tunnel.

State media showed ambulances standing by at the mine entrance and crews equipped with oxygen tanks heading underground.

More than 300 people were working inside the mine at the time of the collapse, and most were brought to safety.

China has long had the world’s deadliest coal mines but safety has improved considerably with more modern equipment, better training and the closure of most of the smallest, most dangerous mines.

The country is by far the world’s largest coal consumer and the amount it mined increased by about 3% in 2017.

While some coal projects have been cancelled as China struggles to clear polluted skies, coal remains key to providing heat and powering the economy.