Premier Wen Jiabao has called for an investigation into possible collusion and corruption that might have led to a coal mine disaster in Shanxi which trapped at least 57 miners underground. State safety chief Li Yizhong quoted Mr Wen as saying at a meeting with rescuers on Tuesday that recovery efforts should be beefed up, China News Services reported yesterday. 'Evidence shows that the May 18 accident not only involves the problem of hiding [the number of miners trapped], but also collusion [between the mine owner and officials] and corruption,' the report said. The accident, described by Mr Li as the worst this year, happened last Thursday when a flood swamped the Xinjing Coal Mine in Datong city's Zuoyun county. Mine owners initially tried to cover up the incident by reporting only five workers trapped. Officials later raised the figure to 57. But in a document to all coal mine officials in the country, made public on the website of the State Administration of Coal Mine Safety yesterday, it said initial investigations found that up to 260 workers were working underground before the accident. The document did not mention how many of them escaped or were rescued. No death toll has been released so far. The news came as a mainland report quoted relatives of trapped miners as saying more than 100 workers could be trapped. An employee of the Zuoyun county government office denied the report and said the number remained 57. The coal mine safety document attributed the incident to the mine operating 'seriously' above capacity. It said the mine, built in 1992, churned out about 100,000 tonnes of coal in the 21/2 months before the accident, surpassing its annual capacity of 90,000 tonnes. Mismanagement and mining a seam outside the mine's approved operating range were also blamed. Bai Yulong , a spokesperson for the rescue operation, said the authority had frozen 11 bank accounts worth 11 million yuan held by the mine owner and other relevant people, Xinhua reported. Nine people, including the owner Li Fuyuan, had been arrested while two others were still in large. In Henan, authorities were hunting the owner of an illegal mine in Chencun village, Shengchi county, where a gas explosion killed eight miners and injured one on Monday night, the China News Service reported yesterday.