Hacking of websites is "nothing short of terrorism" when it endangers peoples' lives, and such acts should hence be taken seriously, Law Minister K. Shanmugam said on Wednesday.

Addressing some 75 SIM Global Education students at a dialogue at Singapore Institute of Management, he was responding to a question from the floor on the recent defacement of government websites.

Painting a picture of how hacking could cause harm, the minister said that if hackers shut down the power grid, doctors in hospitals and air-traffic controllers might be prevented from doing their work, and lives could be lost.

He also cited the example of the Singapore Art Museum, which announced earlier on Wednesday that the email addresses and phone numbers of as many as 4,000 people from its website was recently illegally published and uploaded to a New Zealand-based server.

The minister invited his audience to consider what would happen if it had been medical records or school records that were stolen and exposed.

Hacking into Government websites and disrupting government services is akin to an attack on Singaporeans, he added, since these exist for the benefit of citizens.

He also likened the hackers' act to those of people who would threaten to set fire to others' homes to get their way.

A 35-year-old Singaporean, James Raj Arokiasamy, was charged in court a week ago for allegedly defacing the Ang Mo Kio Town Council website last month.

Hiding behind the "Messiah" moniker, he is also believed to have created the Oct 29 YouTube video threatening a wave of cyberattacks in protest against licensing rules for news websites.

Separately, five men are being investigated for the hacking into the Prime Minister's Office and Istana websites.

Mr Shanmugam added that the recent cases resulted only in the affected websites being defaced, but they could cause a loss of confidence in Singapore's information technology (IT) resiliency.

Since IT is the backbone of many services, the consequences could be dire, he added at the event jointly organised by the government's feedback arm Reach and SIM Global Education.

Earlier on Wednesday, Minister for Communications and Information Yaacob Ibrahim wrote in a Facebook post that Singapore has been under "cyber attack" since earlier this month.

"Any forms of cyber attacks or threats are actually threats on the people regardless if the intent was malicious or mischievous," he added.