Two men in a long-running online vice ring case appealed on Friday against their jail sentences for commercial sex with a minor.

Justice Choo Han Teck deferred his decision to Aug 30 after listening to the arguments presented by the appellants and the prosecution.

Ex-portfolio manager Ng Guan Mean, 38, and former financial planner Kenny Sim Choon Wee, 40, were among 51 men charged with having commercial sex with the same underage escort.

They are the first two to appeal against their sentence.

Ng, who suffers from major depression, had been given nine weeks for paying $450 for the girl's sexual services at M Hotel in Anson Road on Oct 2, 2010.

Sim, who has spastic cerebral palsy and walks with a stick, had been sentenced to eight weeks for paying $500 to the minor for her services at Hotel 81 Bencoolen on Oct 18 the same year.

So far, 20 men have been sentenced to between eight and 19 weeks' jail for commercial sex with the minor. Except for Swiss national Juerg Buergin who claimed trial, the rest had pleaded guilty.

The escort's pimp, Tang Boon Thiew, is also behind bars for pimping offences.

Both Buergin and Tang lost their appeals recently, but the former Swiss banker is taking his case to the Court of Appeal to settle a "public interest" issue.