SINGAPORE - Two school friends who sneaked into crowded shops to take upskirt videos of teenage girls were each jailed for 12 weeks on Friday.

Lee Yi Jie and Patrick Sim Yuan Xing, both now 20, would pretend to reach for items on the lower shelves before filming women on their smartphones - then upload their videos on a website called sammyboyforum.com.

District Judge Mathew Joseph said the case had a "chilling dimension" and called the site "a thriving community of like-minded and depraved individuals ... commenting on each other's perverse handiwork".

The pair, who have known each other since Secondary 1, committed the crimes in 2013 within a span of one month.

Lee faced 45 charges, with nine proceeded and Sim faced eight with three proceeded.

In mitigation, Defence Counsel Eddy Hirono said that Lee, who was 19 at the time of the offences, had done so in "a period of youthful folly".

He added that Lee has since "refocused on his studies" and received the Edusave Awards for Achievement, Good Leadership and Service.

Seeking probation, Defence Counsel S R Shanmugam said that Sim, who was 18 at the time, was facing pressures in his job at an events management company.

He added that Sim had been a good student in school and had contributed to community service.

Noting the rise of upskirt cases, from 387 cases in 2009 to almost 600 in 2013, the judge stressed that it is in strong public interest to impose a sentence that would also deter future offenders.

The maximum penalty for insulting modesty is one year's jail and a fine.