China Mobile, China's largest telecom operator, was found to have had problems in bidding and investment involving billions of yuan, according to an audit report released by the National Audit Office on Friday.

The telecom operator, already reeling from scandals in recent years in which a dozen senior executives were investigated for financial irregularities, was accused of not effectively supervising its subsidiary companies. Its anti-graft system has not been enforced and has loopholes, the office said in the report.

China Mobile's subordinate companies were found to have problems in accounting and financial management. Economic losses were incurred due to chaotic inner management, according to the report.