A High Court judge who raised the sentence for a man convicted of sexually assaulting his Taiwanese friend has voiced disdain for the "offensive" submissions made by the offender's lawyer to downplay his role.

Judicial Commissioner See Kee Oon said the "obvious insinuations that the victim was a woman of questionable morals who had somehow led the offender on and caused him to think that she liked him" were factually inaccurate and without basis.

Ng Jun Xian, 20, had attacked the victim, 23, at a hotel in November 2014, after getting to know her at a club a few weeks earlier.

Ng, a national serviceman, was initially sentenced to seven years' jail and six strokes of the cane for sexual assault and attempted rape by a district court in October 2015.

But in July last year, Judge See increased Ng's punishment for the sexual offences to 81/2 years' jail and nine strokes of the cane.

In decision grounds issued last week, the judge noted that Ng's lawyer A. Rajandran had tried to shift some blame to the victim.

Judge See said: "Having regard to the offensive nature of the submissions made, I am compelled to remind counsel to refrain from making baseless submissions that disparage the character, integrity or morality of a victim ..."

Ng had met the victim, who was here on a tourist pass to visit her boyfriend, at a club along Orchard Road. The offences occurred in a Lavender Street hotel, where he had taken her on Nov 8, 2014, after drinking at the club until 4am with another friend.

Among other things, Judge See said suggestions that the victim was not just an ordinary tourist who was in Singapore for the innocuous purpose of visiting her boyfriend, but "was in fact working as a hostess in the club," were "seldom helpful in the context of sexual offences".

He added that such submissions "will often be a disservice to the accused, especially one who has pleaded guilty and accepted he has committed an offence, because they invariably reflect a startling lack of remorse and insight into his behaviour".

The judge also agreed with Deputy Public Prosecutors Mohamad Faizal and James Chew that there were several aggravating factors supporting a stiffer jail term.

He accepted that apart from kneeling before the victim to apologise shortly after the assault, there were no other clear indicators of "genuine remorse".

"The manner in which he had strenuously attempted to downplay the seriousness of his conduct suggested otherwise," said Judge See.

He sentenced Ng to 81/2 years' jail and six strokes of the cane for the sexual assault charge.

For attempted rape, Ng was concurrently sentenced to four years' jail and three strokes of the cane.

Ng's two weeks' jail term for an unrelated charge of riotous behaviour imposed in the State Courts remained unchanged and was to run consecutively.

Ng had also appealed for reformative training. But Judge See said "the severity of the offences" was enough to conclude he was unsuitable for reformative training as punishment.