China has not audited over 4 trillion yuan ($639.6 billion) of assets held by State-owned enterprises (SOE) overseas, China Youth Daily reported Tuesday, highlighting difficulties faced by the government when expanding its anti-corruption drive to SOEs.

Centrally administrated SOEs' overseas assets are "basically not audited," the newspaper cited Dong Dasheng, the former deputy auditor general of the National Audit Office (NAO), as saying.

The value of assets at around 110 central SOEs totaled 35 trillion yuan by the end of 2013, in which 12.5 percent were located overseas, according to the State-owned Assets Supervision and Administration Commission. That means around 4.3 trillion yuan in assets was not subject to any detailed government audit.

Meanwhile, of around 110 central SOEs, 57 are audited by the NAO and the remainder are subject to various authorities, according to Dong, who is a member of the 12th National Committee of the Chinese People's Political Consultative Conference.

"This does not satisfy the legal responsibilities of the auditors," Dong said.

He suggested all SOEs, including their foreign investments, be audited every one or two years, with a particular focus on revenue and expenditure.

Major reorganization, acquisitions, disposals, transfers and significant projects should be subject to "special auditing tracking," he said.

China's anti-graft authorities will inspect all major SOEs this year, the Xinhua News Agency said in January.

Full accounting of overseas assets is likely to be of interest for anti-­corruption investigation, analysts said, but they questioned whether it would shed much further light on the overall state of SOE balance sheets.

"I would be very surprised if this changes the overall audit result," said Helen Qiao, an economist at Morgan Stanley.

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