Sixteen workers died and one is in a critical condition after being trapped underground in a coal mine in southwest China on Sunday, reported state broadcaster CCTV.

A conveyor belt caught fire in the early hours of the morning, state news agency Xinhua cited the government as saying, which produced dangerous levels of carbon monoxide.

Medics are fighting to save the life of the remaining survivor, CCTV reported.

The cause of the accident is still under investigation, said the Qijiang district government on social media platform Weibo.

The facility, Songzao Coal Mine, is owned by state energy firm Chongqing Energy and located just outside the city of Chongqing. 

Mining accidents are common in China, where the industry has a poor safety record and regulations are often weakly enforced.

At least 14 miners were killed in a coal and gas blast last December at a mine in southwestern Guizhou province.

In December 2018, seven miners were killed in Chongqing after the connecting segment of a skip broke and fell down a shaft.

In October the same year, 21 miners died in eastern Shandong province after pressure inside a mine caused rocks to fracture and break, blocking the tunnel and trapping the workers. Only one miner was rescued alive.