The gas explosion happened on Saturday afternoon at the state-owned Xialiuchong colliery in Hunan province`s Hengyang while 35 miners were at work, the report said.
One miner who had remained alive was later found dead, it said. The six survivors have been sent to hospital.
Luo Lin, the head of the State Administration of Work Safety, and Hunan governor Xu Shousheng have arrived at the site of the accident to oversee the investigation, Xinhua said.
The mine had been operating legally, it said. Many disasters happen at illegal mines, or those that the government has closed down and have then been surreptitiously reopened.
China`s mines are the deadliest in the world, due to lax safety standards and a rush to feed demand from a robust economy.
In 2010, 2,433 people died in coal mine accidents in China, although this was an improvement on the toll of 2,631 a year earlier.
Reuters/H-RN
Editor: Jafar M Sidik
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