One reason a key staff member in charge of SingHealth's cyber security did not alert management was that it would have meant more work and pressure, and leave him and his team with "no day, no night" for anything else.

It was revealed yesterday during the Committee of Inquiry looking into the country's worst cyber attack how Integrated Health Information Systems' Ernest Tan Choon Kiat worried about the extra work, in a group chat involving his colleagues.

"Once we escalate to management, there will be no day, no night," he had posted. It was his job to sound the alarm on suspicious cyber activities.

June's SingHealth cyber attack compromised the personal data of 1.5 million patients and the outpatient prescription information of 160,000 people, including Prime Minister Lee Hsien Loong.

SEE HOME: Team would have 'no day, no night' if I raised alert: Exec