China's safety watchdog said on Thursday it has punished 133 people who were held responsible for five serious accidents that claimed 249 lives.

Meanwhile, three private coal mines involved in these accidents were fined more than 30 million yuan (3.9 million U.S. dollars) each.

Fifty-one people have been transferred to judicial departments while the other 82 government officials at city and county levels have been disciplined, said Chen Changzhi, Vice Minister of the Ministry of Supervision, which supervises the performance of government officials.

The largest single accident was a mine blast in Hebei Province on December 7, 2005, which killed 108 people. The other accidents, each of which claimed more than 30 lives, occurred in Shaanxi, Shanxi and Yunnan and Chongqing Municipality.

The extremely serious accidents should be taken as "lessons that have come at the cost of blood and lives," said Li Yizhong, head of the State Administration of Work Safety (SAWS) at a conference jointly held by the administration and the Ministry of Supervision.

Investigations show the accidents inflicted direct economic losses of 95.14 million yuan (12.37 million U.S. dollars).

The enterprises responsible were all found to have violated work safety laws and regulations, the release said.

The investigation into the Hebei mine blast revealed the coal mine was operating under a mining license that had been fraudulently altered.

Three mine blasts in the provinces of Hebei, Shaanxi and Yunnan occurred in coal mines that were operating illegally after they had been ordered to halt production.

Some local administrations failed to properly supervise the mines, and some officials were corrupt, said the safety administration.

The mine blast in Yunnan could have been prevented if the local government had forced the company to cease production after the State Administration of Coal Mine Safety and the provincial government ordered its closure.

In Hebei, two deputy directors of the local public security bureau were found to have accepted bribes to help the mine owner escape.

Except for a bus accident occurred in Chongqing Municipality, the other four accidents occurred in coal mines, a major cause of concern for the government.

The SAWS figures show that coal mine accidents killed 4,746 people in China in 2006. On average, 17 miners lose their lives everyday in Chinese coal mines, which are the world's deadliest. In 2005, the death rate in China's coal mines was 2.81 for every million tons of coal mined, 70 times worse than the rate in the United States and seven times higher than that in Russia and India.

Small coal mines account for a third of all the coal mines in China, but feature in two thirds of the total deaths every year.

The government has pledged to close 4,000 small mines with production capacities below 300,000 tons before the end of this year, and retain only 10,000 small coal mines by the year of 2010.

However, the death toll from coal mine accidents rose 2.1 percent in April.

Three severe accidents that killed more than 30 people each have occurred since mid March, including two mine gas blasts and the death of 32 workers in Tieling City when a steel ladle -- used for pouring molten steel -- suddenly sheared off the iron rail linking it to the blast furnace.

Li acknowledged the country still faced serious work safety problems.

"We should first impose more severe punishments on those responsible for the accidents," Li told the conference.

He cited the 12-year jail term handed down to Liu Yongxin, former deputy head of the Zhangjiachang Township in Zuoyun County of Shanxi Province, and the 16-year term for Li Fuyuan, coal miner, for their roles in the cover-up of a mine accident that claimed 56 lives in May last year.

Li said a nationwide campaign would be conducted from May to September to identify and close safety loopholes in a bid to curb accidents.

He also pledged to finish investigations into severe accidents within six months, as stated in a new regulation on the reporting, investigation and punishment of accidents in production that is to come into effect on June 1.

Zhao Tiechui, director of the State Administration of Coal Mine Safety, said at the same conference that the May 5 gas blast at Pudeng Coal Mine in Shanxi Province was directly caused by a lack of ventilation that helped the gas build up, again a violation of regulations.

People in charge of the mine had lied about the real situation and offered fake evidence in the investigation by local administrations, said Zhao, who has just returned from the scene of the latest coal mine accident that had left 28 dead and two missing.

The mine was in a mess and under poor management, said Zhao, only two of the 28 miners killed had singed contracts while the 125 miners who were underground at the time when the blast occurred had been hired by five different contractors.

Hao Yingjie, owner of the Pudeng coal mine, had been taken into police custody, he said.

Zhao said the administration would launch a thorough investigation into the accident.