BEIJING (REUTERS) - China's top anti-graft watchdog said Friday it had carried out inspections at six major state-owned enterprises in industries ranging from energy to construction, as the ruling Communist Party expands its anti-corruption dragnet.

Energy giant China Huaneng Group, steel producers Baosteel and Wuhan Iron and Steel, China State Construction, China Shipbuilding Industry Corporation, and China Ocean Shipping Company were the latest firms to be probed by the Central Commission for Discipline Inspection (CCDI), the agency said late on Friday.

The watchdog did not name any executives as targets for individual inspection in its statement Friday but said it warned companies against transgressions such as nepotism, wasteful spending and improper bidding on contracts.

As part of President Xi Jinping's two-year, multi-phase crackdown on corruption, the CCDI has pledged to inspect "all important backbone state-owned firms and financial institutions" this year.

The watchdog brought down more than 70 senior officials at state firms in 2014 and has carried out inspections in the energy, telecom and financial sectors. A total of 26 firms will be inspected, CCDI said.