A former financial planner who had commercial sex with a 17-year-old prostitute was sentenced to eight weeks' jail on Monday. Kenny Sim Choon Wee, 39, is appealing his sentence.

The father of three admitted to paying $500 to the minor for her sexual services at Hotel 81 Bencoolen on Oct 18, 2010.

He was among 51 men in the high-profile online sex case to be brought to court for commercial sex with the minor. He became the 18th man to be dealt with so far.

A district court heard that Sim, now unemployed, became acquainted with the website operated by online vice ring operator Tang Boon Thiew in 2010. Tang is also appealing against his sentence.

Sim sent text messages to Tang to book the minor's services that day. He met the minor at the hotel in Bencoolen Street where they had sex. He paid her $500 and did not verify her age.

His lawyer Anand Nalachandran had sought a heavy fine for his client and urged the court to exercise judicial mercy on account of his client's medical condition. Born premature, he said Sim has a medical history of cerebral palsy and limb spasticity.

Sim had a number of falls in recent years which made his condition worse and jail sentence would be hard on him, he added. The prosecution pointed out that the prison would be able to manage his medical conditions.

District Judge Chay Yuen did not find any exceptional circumstances to depart from a non-custodial sentence. But he he took into account Sim's medical conditions and gave him eight weeks instead of the nine to 13 weeks which the other 17 men got.