Rescuers trying to save 57 miners trapped in a flooded Chinese coal pit began a frantic fourth day of work Monday as officials said the mine was operating illegally.

"One thing that we are certain is that the mine seriously violated the law in digging several layers deeper than permitted," Li Yizhong, head of the State Administration of Work Safety said Monday.

Water from an adjacent abandoned mine flooded the pit in the Xinjing mine in Shanxi province late Thursday.

The flooding occurred after miners used explosives to clear rock, Li said in an official report posted on the administration's website.

According to Xinhua news agency, nine managers have been arrested but police are still searching for the boss who has gone into hiding.

Immediately after the accident, the mine reported that four workers were missing. But that number rose to 57 by Sunday evening.

"In this sense, the actual situation of the accident was covered up," Xinhua news agency quoted Gong Anku, head of Shanxi province's industrial safety bureau, as saying.

The numbers of trapped miners could rise further "because disorderly mine management meant it was unclear how many people were in the mine," the state-run China Daily said Monday.

The mine was operating at over 10 times its licensed output level and producing in one month the amount of coal it was licensed to produce in a year, the newspaper added.

Meanwhile, rescuers confirmed that five workers were dead after their small coal mine collapsed in a rural area 120 kilometers (75 miles) southwest of Beijing.

The five had been repairing a section of the shaft when it collapsed early Thursday, burying all of them, Xinhua said.

As China's demand for coal to drive its booming economy has skyrocketed over the past decade, mining accidents and fatalities have become routine.

China's coal mines are regarded as the most dangerous in the world, with official figures estimating that nearly 6,000 workers were killed last year.