Sixteen workers have been killed by excessively high levels of carbon monoxide in a coal mine in southwestern China, according to authorities and state media.

A total of 17 people were trapped in the mine located just outside the city of Chongqing. One person was taken to a hospital, and the others showed no signs of life, the Chongqing municipal government said in a social media post on Sunday.

State broadcaster CCTV said doctors were fighting to save the life of the one survivor.

State news agency Xinhua said the dangerous levels of carbon monoxide were produced after a conveyor belt caught fire. An investigation was under way, it added.

The facility, Songzao Coal Mine, is owned by state energy firm Chongqing Energy, according to AFP news agency.

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

At least 14 workers 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 of 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.