Singapore accounts for a disproportionate number of Asia's webpages containing images of child sexual abuse, a disturbing trend that experts say needs close monitoring.

The island's tally made up 12 per cent of nearly 2,000 such webpages hosted across the continent last year, Britain-based charity Internet Watch Foundation (IWF) found.

The majority involved children aged 10 and below. Some of the photographs and videos depicted sadism, penetrative sexual activity or such activity with an animal.

Such Singapore-hosted webpages almost doubled in the first 10 months of this year, to 412. This is up from 211 last year, and 10 and 13 in 2015 and 2014 respectively.

The jump, which comes amid a worldwide increase, worries experts here who said an attraction to child pornography could lead to paedophilia if not treated.

"Those who view sexual abuse imagery of children may start off being curious due to its availability online," said clinical psychologist Matthew Woo, who also treats sex offenders. "If they continue, it will escalate, and they could develop paedophilia."

Last year, the Ministry of Social and Family Development investigated 107 cases of sexual abuse involving children, up from 82 in 2015.

STRICT ACTION Sites that are used to facilitate illegal activities will be restricted for public safety and security reasons. INFOCOMM MEDIA DEVELOPMENT AUTHORITY SPOKESMAN

Others noted that the hosts of the webpages may not be physically based in Singapore, which is a hub for webhosting services. Therein lies the difficulty of nabbing the perpetrators.

Said Association of Criminal Lawyers of Singapore president Sunil Sudheesan: "While the police can take action if they come to learn of obscene material on Singapore-hosted URLs, the issue is identifying the perpetrators. Anyone can buy a domain space and hide behind anonymity."

Cyber security researcher Lam Kwok Yan said it is easy to use a complex networking approach to hide one's physical location.

IWF, which focuses on removing child sexual abuse images, said globally, over 57,000 URLs last year were found to have such images, or links to it or to advertise it. Of these, 92 per cent were hosted in five nations: the Netherlands, United States, Canada, France and Russia.

IWF data and the charity did not say how many websites the Singapore-hosted URLs belonged to. One website may have multiple URLs.

When IWF identifies such webpages, it passes the information to Interpol which then liaises with the host countries, its director of external relations Emma Hardy told ST. Local authorities work with Internet service providers (ISPs) to have the content removed if it is deemed illegal under domestic laws.

When contacted, the Infocomm Media Development Authority (IMDA) said it works with ISPs to restrict public access to a limited number of sites as a "symbolic statement" and updates the list from time to time.

However, "sites that are used to facilitate illegal activities will be restricted for public safety and security reasons", said a spokesman.

She added that ISPs are required to exercise judgment to ensure that their content and services comply with the local regulations.

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These include the Class Licence conditions, where ISPs, when required by the authorities, are to prevent user access to content found undesirable, harmful or obscene. Under IMDA's Internet Code of Practice, a licensee is to use his best efforts to ensure prohibited material is not broadcast here.

The police said they take action on cases where necessary, after assessing the facts after a report is lodged. ISPs StarHub, M1 and Singtel said they cooperate with the authorities to restrict access to sites containing objectionable material.

Putting up obscene content online may be an offence under the Films Act or Undesirable Publications Act, which define "obscene" films as ones that "tend to deprave or corrupt" a person. It is also against the law to keep or sell pornographic material.