China's state auditor has uncovered falsified revenues and profits in the accounts of some of the country's biggest state-owned companies, as Beijing broadens its assault on official corruption.

The National Audit Office said on Sunday that 14 state-owned groups, including well-known names such as State Grid, China Ocean Shipping (Cosco) and China Southern Power Grid, falsified nearly Rmb30 billion ($4.8 billion) in revenue and nearly Rmb20 billion in profits in 2013.