"Some died on the spot, while others who were badly injured breathed their last under the rubble", Atique said.
Commissioner Quetta Division Jawaid Anwar Shahwani said the first incident occurred in Marwar, 45 kilometer east of Quetta due to a gas explosion after accumulation methane gas when the victims were working inside the coalmine.
He said two other labourers died in a landslide in an another mine nearby.
Mine inspector Iftikhar Ahmed said Sunday that five more bodies have been recovered from one of the mines, bringing the death toll from the blast the day before to 16. Two workers were rescued in an unconscious condition, while bodies of two miners were recovered Saturday night.
Sources said that after the gas explosion, a huge fire broke out in the Marwar mine causing it to collapse. All the injured miners were rescued and taken to the hospital.
The demonstration culminated with the adoption of a resolution by the participants, calling on Chief Justice of Pakistan Mian Saqib Nisar to take suo motu notice of the mine accidents.
It urged the government to ratify the Safety and Health in Mines Convention of the International Labour Organisation.
The Pakistan Central Mines Labor Federation told the BBC that an average of 200 miners die in mine disasters every year.
In the other incident, at least nine miners were trapped in a coal mine Pakistan Mineral Development Corporation (PMDC) in the Sur-range field near Quetta, an official said.