Quetta: Twelve miners were killed and six rescued after an explosion in a coal mine in the Zardalo area of Balochistan's Harnai district, officials said.

The explosion took place on Wednesday due to leakage of methane gas, they said.

As a result of the explosion, 18 miners were trapped inside the mine. A rescue operation was launched but only six of them could be pulled out while the remaining 12 died, according to the officials.

The rescued miners were found unconscious.

Balochistan chief inspector of mines Abdul Ghani Baloch said methane gas accumulated overnight in the mine, leading to the explosion.

"The rescue operation has been completed by the government mining department and the disaster management agency and all 12 bodies have been recovered and sent to the hospital," he said.

Abdullah Shahwani, the province's director general of mining, also confirmed the death toll in the mine cave-in some 80 kilometres east of Quetta.

Deaths of miners are frequently reported in the mineral-rich Balochistan province where, according to Shahwani, unregulated mining is a major problem.

"In these unregulated mines, there is a dearth of safety measures and working conditions are poor," he said.