The admission followed days of denials after state-run media reported that more than 200 miners died in flooding in a tin mine.
The main Communist Party newspaper, People's Daily, said the owner of the mine has been detained.
On Saturday, the People's Daily said that "initial investigations indicate more than 70 people died" in the accident.
The mine was flooded when the workers drilled into a disused shaft that had been filled with water to prevent it from collapsing, the newspaper reported.
The miners "had no way to escape", it said.
Cover-up
Chinese state media on Monday said the mine's owners and regional authorities had tried to cover up the extent of the disaster.
Several Chinese journalists said local officials had prevented them from investigating the incident.
The Shanghai Youth Daily alleged local officials were playing down the scale of the disaster and said the mine company had paid the victims' families 20,000 yuan ($2,400) to stop them talking to the media about what had happened.
A local villager told the Wenhui Daily there were five groups of 40 miners and 10 safety supervisors underground when the accident happened.
A pit official said the mine is worked 24 hours a day by miners who dig for tin in three shifts 700 metres (2,300 feet) below the ground.
Poor safety record
A BBC correspondent in Beijing says mining accidents are common in China - it has the worst record for industrial accidents in the world - and local officials often try to cover them up.
Mining accidents claim as many as 10,000 lives in China each year.
Last week, 92 miners were killed after an explosion at an illegal coal mine in Jiangsu province in eastern China.
Last month, the government launched a crackdown on tens of thousands of illegal, privately-run mines and ordered all small, state-owned mines to close for safety checks.
Most miners come from poor rural areas with high unemployment, and are willing to jeopardise their lives to earn a living.