Safety watchdogs fined hazardous coal mines a total of 333 million yuan (.5 million) in the first seven months of this year, almost double the same period in 2016.
Authorities issued 3,967 administrative penalties - including fines - between January and July, an increase of 91.7 percent year-on-year, according to data released on Saturday by the State Administration of Coal Mine Safety. Fines alone were up by 93.9 percent, it said.
The top watchdog said the sharp increase is the result of safety inspectors visiting more mines than in previous years, while provincial-level authorities have also been evaluating mining practices and carrying out surprise checks.
Inspections have been conducted at 6,431 businesses this year, 1,411 more than in the first seven months in 2016, according to the data.
A total of 102,977 hazards were uncovered, including 171 major safety violations - hazards so dangerous or complex they cannot be solved by temporary or permanent suspension but instead require long-term attention.
Managers have also been held accountable and punished, even if no casualties were reported at their mines, such as in Heilongjiang province, where 15 managers were removed from their posts after the discovery of eight safety hazards, the top watchdog said.
The number of reported workplace accidents in China fell by 25.4 percent year-on-year to 22,400 from January to June, while fatalities dropped by 17.4 percent to 16,200, according to a statement in July from the State Administration of Work Safety.
The administration did not disclose the number of accidents or fatalities associated with coal mines, but it did say both had seen a decline.
However, Xue Jianguang, a spokesman for the administration, said at a recent news conference that China still faces challenges in ensuring the safety of coal production, especially at small mines.
"It's been a problem that some small mines violate laws and regulations and continue to operate after being ordered to suspend production," he said.
Of the seven major accidents reported at small coal mines in the first six months of this year - accidents that kill 10 to 30 people, or severely injure 50 to 100, or result in direct economic losses of 50 million to 100 million yuan - three were at mines that had resumed operation without official approval, he said.
The administration will continue to close small coal mines with an annual output of less than 90,000 metric tons, Xue added.