At least 12 people were killed and dozens injured in a huge fire which broke out when a gas cylinder exploded in Pakistan's restive Balochistan province, media reports said on Tuesday.

The cylinder exploded while being refilled at a filling shop in the Lasbela district of the southwestern province on Monday, the Dawn newspaper said.

The flames engulfed other gas cylinders in the shop and spread to other shops, destroying at least four of them and around two dozen motorbikes parked in the vicinity, the paper added.

Two people were killed on the spot while 10 others succumbed to injuries during the treatment at a hospital, Geo News reported, quoting the police.

At least 25 people were severely burned in the fire. They were shifted to Karachi's Dr Ruth Pfau Civil Hospital.

According to a doctor attending them, the condition of some of the injured was critical with 70 to 90 per cent burn injuries.

The death toll is expected to rise, police said.

Lasbela deputy commissioner Murad Kasi said with the efforts of firemen, the entire bazaar was saved from burning and that an inquiry has been initiated to fix responsibility for the incident.