Police feared the death-toll at Lalmatia coal mine in Jharkhand state would eventually reach 23 after the Thursday incident, spokesman RK Mallick told news agency AFP.

"Besides the challenging terrain and foggy weather, the cave-in area is spread around 300 meters (980 feet) and it's obviously taking time to clear the debris and search for the unaccounted miners," Mallick said.

Rescuers were forced to work delicately to avoid a further collapses at the Godda district mine.

"We are carrying on the rescue operation in a systematic manner so that the situation does not aggravate as the debris is too much and it should not fall," R R Mishra, chairman and managing director of the mining company said.

Baleshwar Mahato, a bulldozer operator at the open cast mine site whose son died in the collapse, accused the mine's operators of ignoring two safety warnings before a massive mound of earth came crashing down on excavators

"After that first warning, there was another alert around 6 p.m. (on Thursday), when a bigger chunk of mud slid down," Baleshwar told "The Indian Express."

"But work continued where Kuleshwar (his son) was and then, this tragedy struck."

Authorities launched an investigation into the cause of the incident at Eastern Coalfields Ltd's mine.

The last major mining accident in India was in 1975, when 372 workers were killed after the Chasnala mine in Dhanbad was flooded.

Compared to neighboring China, India has a relatively safe record for mining-related accidents. China averaged about 1,000 fatalities every year. In 2015, India recorded 38 deaths across 570 mining sites.

aw/se (AFP, PTI)