Concerns over the increasing problem of voyeurism have prompted law changes that will make it a separate sexual offence with heavier punishments, possibly caning, said Home Affairs and Law Minister K. Shanmugam.

The changes to the Penal Code will be debated in Parliament today.

Mr Shanmugam said: "It shows that the Government is taking this very seriously. It is also a psychological, philosophical setting out that this is very serious."

His comments came in the wake of the controversy over the way the National University of Singapore (NUS) and the police handled a case in which an undergraduate was filmed without her consent.

Ms Monica Baey, 23, had taken to social media to express her frustration at what she felt was too light a punishment for the fellow student who filmed her secretly while she was taking a shower at the university's Eusoff Hall.

Police gave the student, also 23, a conditional warning.

Mr Shanmugam, referring to the case, told The Straits Times last Thursday that the Criminal Law Reform Bill will give greater possibilities for punishment in future.

Current criminal law treated Ms Baey's case as insult of modesty, with a maximum punishment of a year's jail.

But under the proposed changes, the non-consensual observation or recording of someone doing a private act will become a specific offence by itself.

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This covers Peeping Tom behaviour, people who make, possess or distribute voyeuristic recordings and those who alter buildings and walls by putting in secret cameras, for example. The maximum jail term for such crimes will be doubled, and caning will also be introduced.

It will also be harder for perpetrators to get away scot-free in cases where victims in the videos cannot be identified. The law will include a presumption that victims did not consent to being observed or recorded, which means those caught with such films will have to prove they were given permission in the first place.

"So where you are punished, it is going to be much more serious," said Mr Shanmugam.

Even then, he added, there was a need for discretion to be exercised, depending on the facts of each case.

"Nevertheless, case by case, the Attorney-General's Chambers and police have to decide whether you punish the person, as in take him through a jail sentence, or take him through criminal charges, or whether in specific cases, you exercise your discretion to give a conditional warning," he added.

"That has got to depend on the facts of each case."

He cited a case where another NUS student had been given a 24-month conditional warning after he was caught filming children in a shopping mall toilet in 2015.

The student was initially prosecuted but the charges were later withdrawn after doctors at the Institute of Mental Health said that he needed mental treatment.

Mr Shanmugam noted that the student had remained crime-free since and added: "Those sort of assessments will have to continue to be made.

"But where the cases are prosecuted, the range of penalties now include caning."

He said the law changes were decided last year because the number of cases involving insult of modesty had gone up: "We felt (it) needed to be tackled."