A total of 48 miners were working underground when the Sigou mine in Shisi township, Xin’an county, was flooded at 11.40pm (1540 GMT) on Friday, Xinhua said, adding that only six miners had managed to escape.
Rescue teams were at the scene, the report said.
The news came as the toll from Sunday’s explosion at the Dongfeng coal mine near Qitaihe city in northeastern China’s Heilongjiang province rose to 169.
Two senior mine officials at the state-run Dongfeng mine were detained this week after the national work safety watchdog angrily rebuked mine management for ignoring vital danger signs in the week leading up to the deadly blast.
China’s mines, many of them illegal, are considered the most dangerous in the world, especially in recent years with demand for raw materials escalating to help fuel China’s rapid economic growth.
Also on Saturday, a coal mine blast killed 16 miners in southwestern China, state media said.
The gas explosion occurred early on Friday morning at Zhonghe Coal Mine at Shuicheng county in Guizhou province, while 31 miners were working in the shaft, the China News Service website reported.
The other 15 workers escaped, the report said.