legal ground
Article 223 of the Criminal Law of People's Republic of China (PRC)
Bidders who collude with each other in bidding quotations and harm the interests of the tenderee or other bidders, if the circumstances are serious, shall be sentenced to fixed-term imprisonment of not more than three years or criminal detention and shall also or only be fined.
Bidders and tenderers who collude in bidding and harm the legitimate interests of the state, collectives and citizens shall be punished in accordance with the provisions of the preceding paragraph.