The Hospital Authority (HA) on Monday said it suspended the use of 16 operating theatres across public hospitals, after screws were found to have come loose on their surgical lights.

Comprehensive checks were carried out on all lighting units made by the Swedish company, Getinge, after one fell from the ceiling of an operating theatre in United Christian Hospital on Saturday, injuring an assistant anaesthetist.

The HA said 16 of the 50 lighting units were found to have potential risks, forcing it to temporarily shut the affected theatres and reschedule some surgeries.

It said it had ordered the supplier to check its lights more frequently, every one to two weeks, while surgical lights made by other companies will also be examined in a couple of days.

The Secretary for Health, Lo Chung-mau, called the incident "absolutely unacceptable", saying he has tasked the HA to look into the case seriously.

"Safety of patients and staff is of our prime concern. This is an extremely serious incident involving high-standard medical equipment for use in operation rooms and it is absolutely unacceptable," Lo wrote in a statement on Monday evening.

"They [the HA] are also tasked to take prompt follow-up actions properly, including immediate inspection of all hoist installations in its facilities based on risk assessment to guard the safety of staff and patients."

The HA said that engineering expert Lam Chiu-hung had been asked to carry out an independent investigation of the incident, but that the supplier will also conduct its own probe.

Medical sector lawmaker David Lam told RTHK it's unusual for a surgical light to fall and a full investigation is needed.

He said the lighting rig that fell had been checked just two months ago.

"So we must investigate into that particular checking. What went wrong during the checking? Was it done according to the protocol; or was there any breach of the protocol? Or have the personnel been fully trained for their job when they checked the OT lights," he said.

"So these are areas that we have to investigate."

A senior HA manager, Yuen Pak-leung, earlier told a radio programme that the authority was checking some 200 hospital lights from the same supplier.

He confirmed that the surgical lights at United Christian Hospital were last checked in December, and this particular model – which weighs around 90 kgs – had been in use for more than a decade.

"The light can move up and down. So as it is hung on the ceiling by the screws, they will be stretched. If you move it a lot, it may become a little loose, this does happen usually," Yuen said.

"So as part of the established procedure, we have annual checks, and if we find that the lights are loose, we will tighten them again."

The head of the Hong Kong Public Doctors' Association, Tony Ling, described the case as shocking, and urged the HA to look into whether there’s a need for a thorough review of the relevant maintenance schedule.