BEIJING -- China's anti-corruption agencies will tighten supervision over domestic companies that attempt to engage in commercial bribery as part of overseas investment projects, a senior discipline inspector said Friday.

The agencies will set up an effective supervision system to regulate the behavior of Chinese companies when they invest abroad and push them to strictly abide by laws, regulations and business codes at home and abroad, said He Yong, deputy secretary of the Central Commission for Discipline Inspection (CCDI) of the Communist Party of China (CPC).

They will also step up efforts to investigate cross-border cases of commercial bribery, he said at a meeting held in Beijing.

Progress has been made in a national campaign against commercial bribery that was initiated 2005, he said.

Between July 2005 and last December, anti-graft agencies cracked more than 100,000 bribery cases involving 26 billion yuan ($4.13 billion), according to He.

However, he warned that controlling commercial bribery remains a difficult task.

In addition to efforts to prevent cross-border bribery, the focus of the agencies' future work will also be placed on investigating government officials who trade their powers for profits and non-government parties that engage in commercial bribery, as well as insider trading and illegal related-party transactions in state-owned enterprises and financial institutions, he said.

They will also work to improve a credit reference network and facilitate information-sharing across multiple regions and industries to discourage bribery, he said.