Health Secretary Lo Chung-mau said on Saturday that the Hospital Authority must get to the bottom of an incident last week in which a surgical light fell in an operating theatre, striking an anaesthetic assistant on the shoulder.

The authority said on Friday that an initial investigation found that six screws holding up the light at the United Christian Hospital in Kwun Tong had broken, likely because of metal fatigue. Problems have now been found with 23 of the 195 lights made by Swedish company Getinge, and Lo said the incident raised "serious alarms".

"Everybody asks the question: the responsibility of the Hospital Authority. Of course, this happened under the Hospital Authority. And the Hospital Authority has the responsibility to investigate into why this happened, to urge the contractor to come up with a report, and explain,” he said.

“If this manufacturer and the maintenance contractor cannot provide satisfactory answer to all these and ensure this will not happen, the Hospital Authority has to seriously consider whether to trust this manufacturer and maintenance contractor anymore.”

He said he was "totally shocked by what had happened" and had never experienced anything like it in his 40 years working as a surgeon.

The authority also said on Friday that it reserved the right to take legal action.

“There is no doubt that the Hospital Authority has the ultimate responsibility to ensure a safe working environment for our staff and also for our patients,” Lo stressed.

No patients were present when the light fell on February 18.