Kwong Wah Hospital said a malfunction in the backup power system for the operating theatres was the main cause of a power disruption on Wednesday evening that affected 25 non-urgent surgeries.

Twenty-three elective surgeries scheduled on Thursday had to be postponed and two other elective surgeries were moved to other operating rooms, the hospital said in a statement.

It said that while the main power supply was working fine, it had decided to shut down eight operating theatres as a precaution.

“Preliminary investigation by the contractor who installed the electricity supply system revealed that there was a malfunction of the control components in the uninterrupted power supply system which is the third tier backup power supply source and this malfunction affected the operation of the third tier backup power supply system in the operating theatres," a spokesperson said.

“Affected by the incident, 23 elective surgeries originally scheduled for [Thursday] needed to be postponed and two elective surgeries needed to be transferred to another unaffected operating theatres. The two surgeries were both performed uneventfully.”

The spokesperson said that the contractor had replaced the faulty components in the system and the Electrical and Mechanical Services Department was conducting independent tests.

It said the affected surgeries were expected to gradually resume.

The hospital added the patient who was moved to another theatre when the outage happened on Wednesday had a complication, but it said that was not related to being moved.