China announced plans to audit foreign assets of its biggest banks, oil producers and other government companies in a new move to tighten control over state industry.

The Cabinet agency that oversees companies including PetroChina Ltd. and China Mobile Ltd. says it will hire outside firms to audit them, though they must be incorporated in China.

The move comes amid a spreading anti-corruption campaign that appears to be aimed at tightening the ruling Communist Party's control over politically influential state companies.

This week, the party announced that the vice chairman of PetroChina, Asia's biggest oil and gas producer, was under investigation.

The official Xinhua News Agency said the foreign assets of China's biggest state companies were estimated at 4.3 trillion yuan ($700 billion) at the end of 2013.