A total of 22 officials are being investigated and one has been arrested, accused of covering up a mine explosion that killed more than 30 miners in Hebei province on July 14, a senior official said on Tuesday.
The blast in the unlicensed Lijiawa mine in Yuxian county was set off by explosives illegally stored down the shaft.
Relatives of the dead were kept quiet with payments and threats, the Xinhua News Agency reported Wednesday.
"An investigation has shown that the mine owners and county and township governments colluded to conceal the accident," acting governor Hu Chunhua told a provincial teleconference on Tuesday.
"This is a shocking case."
After the mine disaster, the corpses were hidden in surrounding areas while grieving families were paid off.
"Cash was used to keep them quiet as well as threats and other means, and the miners and their families were not allowed to reveal the facts to the outside," the report said.
The Hebei provincial government also said Wednesday that three officials in Tangshan city had been fired in light of two coalmine accidents which killed 22 people.
Among them was Han Guoqiang, a deputy government chief of Guye district.
The other two were a township government chief where the two coalmines were located and his deputy in charge of coal mine safety.
On Aug 27, coal yard workers in Wushuizhuang village illegally dug into a coal reserve using an underground tunnel when it suddenly collapsed and killed nine workers.
On Sept 5, an explosion at Xinhua coal mine, also in Guye district, killed 13 miners.
Spokesman Huang Yi of the State Administration of Work Safety said illegal mining, operational irregularities and neglect of safety measures were to blame for nine major incidents in which people had died in the past nine months.
To date, 118 officials and business owners have been held to account for the nine incidents.
Ninety-five of them have been detained and 23 were removed from their posts, Huang told a conference on Tuesday.
Two incidents last month - a fire that killed 44 people in a Shenzhen nightclub and a landslide in Linfen of Shanxi that killed 271 villagers - could involve corruption, but he did not give details pending the results of investigations.
Winter is a critical period of economic development, and all efforts will be mobilized to curb the incidence of major safety incidents, Huang said.
Reporter uncovers the truth
A reporter's blog, which caught the attention of Premier Wen Jiabao last month, helped uncover the truth about a burst mine dam that killed 45 people on Aug 1 in Loufan county, Shanxi province.
At the time, local authorities said only 11 people had died, and the accident was described as a natural disaster.
At the end of August, Sun Chunlong and Wang Xiao, two reporters with the Oriental Outlook magazine, published an article stating that the death toll was at least 41, and not 11.
On Sept 14, Sun further published an open letter to acting Shanxi governor Wang Jun on his blog restating his claim.
Sun even provided a list of names of the 41 miners that died. He obtained the names during a visit to Loufan to get the true story.
"I can even provide the addresses of those who died. I believe what I have uncovered is only a small part of the whole truth about this incident," Sun wrote.
Some local villagers went to the offices of the county government for help to locate their missing relatives, but were detained by the police for up to eight hours.
The report caught the attention of the State Council, and Premier Wen ordered a thorough investigation into the incident.
On Monday an investigation team announced that the disaster was man-made, not natural, and the death toll was in fact 45.
The case is being further investigated.
Agencies contributed to the story