SINGAPORE - A 38-year-old online vice ring pimp who received nearly $2.6 million in revenue and earned about $1 million in profit over five years, in one of the largest online vice ring cases, was on Thursday jailed for 85 months and fined $130,000.

He was also ordered to pay a $152,893 penalty for tax offences.

Chew Tiong Wei had earlier pleaded guilty to 28 charges, and admitted to another 73 for consideration during sentencing.

His vice ring involved at least 22 prostitutes, 11 of whom were below the age of 18 at the time of the offences. Two girls were just 15.

He also had commercial sex with the underage females before prostituting them, reasoning that they had to get used to the "whole feel" of dealing with customers, and he would give pointers and feedback.

In passing sentence, District Judge Lim Keng Yeow said there were multiple aggravating factors in the case, including the scale of Chew's illicit business, the length of time he operated it, and "the very substantial profits involved".

The judge said that the sentence for all cases involving commercial sex offences "must be sufficiently severe to deter their commission so as to uphold public morality".

And in cases where young girls are solicited for commercial sex, he added, the sentence to be passed also has to be "severe enough to adequately ensure their protection".

"We face the sad reality that some misguided minors may be quite willing to turn to prostitution to earn what appears to be easy money. What is equally sad and indeed far more reprehensible is where mature adults, who really ought to know better, will readily draw them into the trade, be a corrupting influence to them and even become perversely enticed by their youthfulness and prey on their relative innocence," the district judge said.

The court had heard last December that Chew first set up his vice business in mid-2007, and operated until he was arrested in his Golden Landmark office in December 2014.

His modus operandi was to take out advertisements to recruit female "social escorts" in newspapers. Interested women would contact him on his mobile number, and he would meet them for an interview.

After an applicant agreed to provide sexual services, Chew would arrange for a photo-shoot of her in scantily-clad clothes and in provocative poses. Naked photos would also be taken if she gave her consent.

He would then create a profile of the "social escort" on an online forum, with a price which he determined based on a discussion with her and his assessment of her "quality".

The prices of the prostitutes ranged from $200 to $1,000.

From 2007 till 2008, Chew earned somewhere between $20,000 and $30,000 by acting as a middleman between the prostitutes and their customers, taking a 40 per cent cut of the escorts' earnings.

In January 2010, due to increasing profits, he created his own website for his illicit business. Chew registered his agency, Prestige Talents Management, with the Accounting and Corporate Regulatory Authority, as a sole-proprietorship providing "social escort services".

He paid $8,000 to a company to design a logo and set up a website for his business. He also paid $12,000 to another company to set up a customised database system, based on SMS messages he sent and received, for his vice business.

In 2012, Chew also got the digital company he had earlier engaged to create a new site for his business.

Based on records on the database, Chew received revenue of over $2.5 million between January 2010 and December 2014. After deducting the payment to the escorts and operating expenses, he earned just over $1 million during the five-year period.

Chew also admitted to five counts of making obscene films of himself having sex with prostitutes in his home without their knowledge.

He pleaded guilty to evading tax by under-declaring his profit for the year of assessment 2012 in his income tax return. He declared his profit to be $40,166, when it was actually $175,779. The tax undercharged amounted to $15,118.25.

He also declared his profit for the year of assessment 2013 to be $20,345, when it was actually $160,417. The tax undercharged amounted to $11,846.40.

In April 2014, Chew also submitted a Productivity and Innovation Credit (PIC) cash payout application form for purchasing a $15,000 software. In the form, he declared that he had met the conditions of employing and making CPF contributions for at least three local employees, and provided the particulars of his father, mother and wife.

They were never employed by Chew, but he had made CPF contributions into their accounts. Chew later obtained a PIC cash payout of $9,000 and a PIC bonus of $15,000.