A 16-year-old was sentenced to reformative training on Wednesday for having underage sex with three girls and assisting in unlicensed moneylending business.

Muhammad Nor Aszroy Zaidon admitted to three counts of having sex with the girls aged 12, 13 and 14 between October 2011 and August last year, and handing over his bank ATM card to his sister's mother-in-law, who worked as a loanshark runner.

A Community Court heard that Aszroy became acquainted with the victims on Facebook and entered into a relationship with them without having met each other in real life.

He was previously let off with a 12-month conditional stern warning in May last year for an October 2011 sexual offence with the 12-year-old girl at a staircase landing in Clementi.

More than a month later, he re-offended.

In July last year, he took a 13-year-old girl he befriended to a staircase landing of his block in Teck Whye Lane where he had unprotected sex with the girl.

The following month, he invited a 14-year-old girl to his flat. As his mother was around, he took her to a staircase landing a floor above where he committed the sexual offences.

Aszroy had appeared before the same judge previously but his guilty plea was rejected during sentencing as he had disputed the charge of assisting in unlicensed moneylending.

In July, both the pre-sentence and Reformative Training Centre reports had been called for and he was recommended for both.

On Wednesday, Community Court Judge Shaiffudin Saruwan agreed with the prosecution that Aszrov should undergo a period of reformative training which is between 18 months and three years behind bars.

Five other charges were considered during his sentencing.