As the country steps up efforts to root out corruption, auditors are playing an important role in tracking down irregularities in State-owned enterprises, and 4 billion yuan ($640 million) of public money has been retrieved so far.

In a National Audit Office report released on Sunday, 13 of 14 SOEs audited were found to have violated rules of procurement and bidding. The money restored was only a fraction of the total haul of the nearly 160 billion yuan involved.

The office said more than 250 people had been disciplined and 56 cases involving "serious violations of Party discipline and laws", had been handed over to anti-graft departments and law enforcement entities.

Sifting through the accounts, the office found false statements of profits adding up to nearly 20 billion yuan in 2013, and another 850 million yuan has been disbursed as allowances for staff.

The audit report also revealed that some senior executives abused the power or influence of their positions.

Xiao Peng, former deputy general of China Southern Power Grid, was found to have traded his power for insider information in the stock market regarding electricity supply companies and to have benefited eight consecutive years with an annual yield of 50 percent.

Auditors also uncovered 5 billion yuan in illegal gains by executives and their family members who possessed information on national resources, development plans and undisclosed information in the stock market.

Liu Jiayi, head of the National Audit Office, said most of the violations took place in sectors involving huge sums of public funding, State assets and State-owned resources, such as land distribution and the mining sector.

Wang Yongjun, a professor at Central University of Finance and Economics, said ensuring accountability should be a priority, and "supervision would be just empty talk if a system with efficient audit procedures fails to be installed in the State-owned giants".

zhang_yi@chinadaily.com.cn