SINGAPORE - A man indulged in a series of bondage, discipline, sadism and masochism (BDSM) sex activities with a 15-year-old schoolgirl after she posted an advert online looking for "someone who (can) afford to pay for my tuition fees".

Lim Chee Keong, 33, met the girl on a website offering commercial sex but never paid her a cent, and went on to have unprotected sex with her despite knowing she was underage.

He was sentenced to five years in jail on Monday (July 9) after being sentenced on four charges - three of sexual penetration of a minor and one of possession of obscene films. Another seven related charges were taken into consideration.

The assistant engineer had told the girl he was fine with her age but asked that she delete all their correspondence to keep their arrangement under wraps.

They first met in the early hours of New Year's Eve 2016 at a staircase landing in Lim's neighbourhood. Lim asked her to perform a sex act in front of him before making her inhale an unknown liquid, which she said made her feel light-headed and hot. He then had unprotected sexual intercourse with her, despite her request that he use a condom.

They met again on Jan 21 last year at Park Hotel Alexandra, where Lim got her to take part in BDSM activities after giving her two glasses of Cognac and soda to ease her anxiety.

He then made her perform an oral sex act on him before binding her wrists behind her back with a leather restraint and whipped her body. He then dripped hot candle wax on her in the bathroom.

They then had unprotected sex twice, with Lim again ignoring the girl's request to use protection.

During the course of their dalliance, Lim demanded the girl send him nude photos and videos, and asked her to comply with his BDSM sexual demands. She refused initially but was lured when he promised to pay her $4,000 to $5,000 a month for a year.

However, investigations revealed that he never intended to pay her. In fact he used a fake name to engage her and also communicated with her using a pre-paid SIM card and discarded it after their sexual encounters.

It was further revealed in court that Lim had engaged over six women in 2016 in the same way, promising to pay them for sex but never actually doing so.

Lim's offences were discovered when the girl's teacher noticed her behaving oddly and sent her to a counselling session. She broke down during the session and admitted what happened. The school lodged a police report and Lim was arrested in February last year.

A search of Lim's home uncovered sexual paraphernalia such as sex toys and leather wrist cuffs. He also had 197 obscene films in his electronic devices and a bottle of sex enhancement drugs.

In mitigation, Lim's lawyer Gino Hardial Singh pleaded for leniency, pointing to his lack of antecedents and how Lim is responsible for the care of his ill, aged father.

For sexual penetration of a minor, Lim could have been sentenced for up to 10 years and be liable to a fine. He is planning to appeal against his sentence and is currently out on bail of $30,000.