Five companies supplying spare lift parts to Housing Board blocks are being probed by the Competition Commission of Singapore (CCS) for anti-competitive practices.
They are suspected of refusing to supply vital parts such as motherboards to third-party lift maintenance contractors here.
This may have prevented the contractors from competing for contracts to maintain and service lifts of particular brands installed in HDB estates.
The CCS can take action against a dominant or sole supplier who refuses to supply certain essential products or services that cannot otherwise be obtained.
There are more than 20,000 lifts installed in HDB estates across Singapore and most are maintained by their original installers rather than third-party contractors.
The Competition Commission of Singapore can take action against a dominant or sole supplier who refuses to supply certain essential products or services that cannot otherwise be obtained.
Town councils are required to carry out regular maintenance of lifts installed in HDB estates and can either appoint the original installers of the respective brands, or call a tender inviting companies, including third-party contractors, to provide maintenance services.
According to the CCS, it may be cheaper to use third parties. Firms that wish to tender for lift maintenance projects that include multiple lift brands would require brand- specific lift spare parts.
The investigation follows another probe into lift supplier and maintenance contractor EM Services.
Two years ago, a complaint was made to the CCS about the company, a joint venture between the HDB and Keppel Land, sparking an investigation.
EM Services was found guilty of refusing to supply spare parts to third-party contractors.
But two months ago, the company finally agreed to sell the branded spare parts to third-party lift maintenance contractors. In view of this commitment, the CCS decided not to take action against it.
CCS chief executive Toh Han Li said: "This will provide more options for HDB lift maintenance, as town councils can choose to call for a single tender for lift maintenance across various lift brands, in lieu of contracting with multiple parties.
"The CCS will continue its other investigations to ensure access to essential lift spare parts for third- party lift maintenance contractors, and (ensure that they can) effectively compete for lift maintenance of these other brands of lifts."
The competition watchdog also encourages all businesses to put in place competition compliance programmes to ensure their business conduct complies fully with the Competition Act.
A string of incidents involving HDB lifts have made the news recently.
In May, a 77-year-old man died in hospital after his mobility scooter toppled as he was backing out of a lift in Pasir Ris Street 21. The lift was not level with the lobby floor when it stopped.
Last October, an 86-year-old resident in Tah Ching Road lost her lower left arm after it was severed in a freak lift accident.
National Development Minister Lawrence Wong announced in Parliament on Monday that all town councils will need to set aside a higher proportion of their monthly service and conservancy charges in their sinking funds specifically for lift replacements.