SINGAPORE - A serial offender, who prowled Yishun housing estate looking for women to take upskirt photographs of, was jailed for 24 weeks on Friday for insulting their modesty.

Malaysian bubble tea shop stall assistant Teo Wei Chek, 20, had admitted to 22 of 84 charges of intruding into the privacy of a woman by placing his mobile camera phone below the woman's skirt and taking photographs.

He committed the offences at the overhead bridge near the Yishun Shell station, HDB staircases , in lifts and on escalators between February and May 1 this year.

The court heard earlier that a member of the public called the police on May 1 this year, saying he had witnessed a man chasing a schoolgirl and taking an upskirt photo of her the day before. He told police to check the man at the void deck of Block 134 Yishun Street 11.

Police came and detained Teo. They checked his mobile phone and found upskirt photographs. Teo then admitted that he had taken many women's upskirt' photographs over the past few months.

He would spot his victims and would often follow them to take the photographs.

At times, he would follow his victims from the void deck into the lift to do so.

He also targeted a number of primary school students in school uniform.

He would approach these girls and tell them that he wished to take photos of their shoes.

When the girls agreed, he would tell them to turn around, and quickly place his cellphone below their skirts.

In another case on Thursday, Goh Eh Chun, a 34-year-old drafter, was sentenced to six weeks' jail after he admitted to three counts of insulting modesty by using his iPhone to film upskirt videos of women.

The court heard that on May 11 last year, he stood behind a 21-year-old woman, who was wearing a short skirt on the escalator of Farrer Park MRT station, and took a video of her underwear without her knowledge.

A 32-year-old sales assistant saw him checking his phone as he reached the top of the escalator. He detained Goh and approached security officers for help.

Goh admitted he had been filming upskirt videos since 2013. Eight other similar charges were considered during his sentencing.

The maximum punishment for the offence is one year's jail and a fine.