The raids were part of a new crackdown on anti‑competitive practices in the trade.
The watchdog said the raids, which took place on Wednesday, included the offices of four building contractors and the residences of the individuals involved.
The contracts in which they were involved have an estimated total value of around HK$500 million.
The commission said the 28 housing estates and buildings are located across Hong Kong, with some projects yet to be awarded, while work on other projects had commenced or had been completed prior to its investigation.
The watchdog said it has been reaching out to relevant stakeholders of the buildings involved in the case.
The latest search operation, codenamed “Hunter”, came after officers found new leads from sifting through evidence collected during the first round of operations in January.
Officers said they found a series of suspicious text messages exposing the potential existence of another hidden bid‑rigging syndicate that attempted to manipulate the outcome of the tender for a building maintenance project.
The conversation revealed that during the project’s tendering process a contractor, who was not previously under investigation, had allegedly scouted for other contractors through middlemen to submit cover bids.
The contractor had also allegedly engaged in anti‑competitive practices in multiple building maintenance projects, including disseminating instructions on bidding prices – commonly referred to as “homework” – for the purpose of manipulating tender results, the commission added.
