The bodies of ten more miners were pulled from a collapsed coal pit in Balochistan city of Harnai on Wednesday, bringing the death toll to 12 after the rescue bid ended, reported 24NewsHD TV channel.

A gas explosion rocked the private coal pit in the mining region of Khost on Tuesday evening, trapping the workers about 800 feet below ground.

"The rescue effort has concluded with the recovery of all 12 dead bodies," Abdul Ghani Baloch, chief inspector of mines for Balochistan province, told AFP. "Two bodies were recovered during the night, with the remaining 10 retrieved early in the morning."

Abdullah Shahwani, Balochistan's director general of mining, also confirmed the death toll, and said "initial reports suggest the incident was caused by methane gas".

Prime Minister Shehbaz Sharif issued a statement expressing "profound sorrow and grief over the loss of precious lives".

It was initially thought that there were only ten miners involved in the cave-in about 80 kilometres east of Quetta city.

Rescue workers from the government mining department and the disaster management agency toiled through the night to reach them.

A group of eight people who were attempting to rescue their colleagues also became trapped for several hours, but were later brought to safety by a government rescue team -- some of them unconscious.

Deadly incidents are not uncommon in Pakistan's mines, which are known for hazardous working conditions and poor safety standards.

Balochistan is Pakistan's largest but poorest province, and is rich in natural resources, which locals have long complained are not shared fairly among their communities.

"This incident is neither the first nor will it be the last in Balochistan," Lala Sultan, head of the Balochistan Coal Mines Workers Federation told AFP.

"Safety measures at coal mines are scarcely implemented. While other provinces have some safety protocols in place, in Balochistan safety is utterly neglected."

In May 2018, 23 people were killed and 11 more wounded after gas explosions tore through two neighbouring coal mines in the same region.

Officials also blamed the twin accidents on a build-up of methane gas which caused an explosion and tunnel collapse.

A total of 43 workers also died in 2011 when gas explosions triggered a collapse in another Balochistan colliery.

Reporter Essa Tarin

With input from AFP