Swiss national Juerg Buergin, convicted of two counts of obtaining commercial sex from an underage escort in the online vice ring case, lost his appeal against the conviction on Friday.

The 41-year-old former banker was found guilty after a trial in April of paying $600 and $650 for the sexual services of the 17-year-old at the Shangri-la Hotel and Mandarin Oriental Hotel in September 2010 and January 2011 respectively.

He was one of 51 men brought to court in 2011 for having paid sex with the girl, who was below 18 at the time. Nineteen others have pleaded guilty and sentenced to between eight and 16 weeks' jail. Two have appealed against their sentences.

Buergin has been serving his sentence of four months and three weeks since May. He did not appeal against the sentence. According to his lawyer, he is due to be released on Aug 12.

Lawyer Selva K. Naidu raised an issue of law - whether his client must have known that the person from whom sexual services had been obtained was under 18 years of age, to be guilty of the offence.

But the trial judge had found in favour of the prosecution that the offence under section 376B(1) of the Penal Code was one of strict and absolute liability.

Justice Choo Han Teck dismissed the appeal.