The accident occurred on Tuesday at the Lisheng mine in the city of Xiangtan in Hunan province, the local government said in a statement on its website.
The toll rose from an earlier 18 confirmed dead with the recovery of more bodies early Wednesday, it said.
It did not say whether any others remained missing but an earlier statement had indicated five more may still be unaccounted for.
The government had earlier said it hoped to find the miners alive. An investigation has been launched into the incident.
The coal mine authority in the county ordered all mines shut until further notice, an earlier statement said.
China's coal mines are among the most dangerous in the world, with safety often ignored in the quest for profits and a drive to meet surging demand for coal, the source of about 70 per cent of the country's energy.
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