Twelve people are now known to have died in a colliery gas outburst on Friday after the discovery of four deaths previously covered up by the coal mine in southwest China's Yunnan Province, local authorities said Monday.

Four more deaths were discovered after inconsistencies were found between the list of miners written before they went underground and the name list of 17 miners provided after the Friday afternoon accident by the Meishan Coal Mine owner in Haidai Town of Xuanwei City, said Ou Guangcai, vice mayor in a press conference.

The gas outburst has so far killed 12, including one who died on the way to the hospital and one in hospital. Three others were injured in the accident while six miners were lifted to the ground safely, said Ou.

The mine owner has been taken into police custody. The owner's bank account has been frozen.