City officials said an explosion on April 7 caused the Xiahaizi colliery in Qujing city to flood, trapping 22 workers.

Nineteen workers were killed and the remaining three are still missing.

The narrow underground space and the mine's complicated layout have hampered search efforts, said a Xiahaizi spokesman.

It is unknown if safety regulations were breached during the construction of the mine, but a delay in reporting the incident was noted by the mayor of Xinhua.

On Friday, a roof collapse at a mine in Guizhou province killed a further seven people, the official Xinhua news agency said.

According to the State Administration of Coal Mine Safety, over the past decade there have been more than 33,000 coal miners killed across China.

So far this year, 45 people have died as a result of coal mining accidents, excluding the Qujing incident.

Heightened attention to safety regulations and efforts to merge smaller coal mines under state-owned operations cut the death toll each year since 2000.

Last year, 1049 were killed in such accidents, compared with 1384 in 2012.

Looking to showcase its dedication to mine safety, the Chinese government has issued constant media updates following the progress of the Qujing investigations and the rescue efforts.

Dozens of reports have been posted on Qujing's website as well as copious posts on Sina Weibo, a microblogging platform similar to Twitter.

Despite the comparatively high numbers, the Chinese bureau of statistics said coal mine fatalities had decreased by one-third since 2011.