A man, who lured underage girls to his house and sexually assaulted them, was jailed for 41/2 years on Wednesday. Emmanuel Lim Chin Pin, 22, who faced 22 charges, pleaded guilty to nine counts of sexual penetration of a minor, indecent act with a child, attempted sexual penetration, cheating by personation and criminal intimidation. He was then working as an operations manager in his uncle's corporate gifts company.

In April last year, he sent out messages to hundreds of girls through social networking site Facebook to ask if they were keen in a part-time job involving a survey with a stipend of $25 an hour. When they agreed, he invited them over to his flat in Yishun.

Once a girl arrived, he would persuade her to have sex with him. He did this with two girls aged 13 and 14. In all, he abused four victims over a two-year period, using the same methods. In passing sentence, District Judge Mathew Joseph agreed with the prosecution that this was one of the worst cases of sexual penetration of a minor in recent times.

It was disheartening, he said, to note that there had been an abuse of the Internet and Facebook by Lim. "The court therefore has a duty to ensure that it remains safe for young people, especially from the clutches of sex predators who prowl the Internet as if it is their own personal hunting ground for easy prey,'' he added. A stiff sentence, he said, was called for to reflect the public's deep disquiet and distaste over sexual abuse perpetrated on innocent young children and teens.

He said he found Lim's actions "dehumanizing and an outrageous affront to the innocence'' of his young victims.

"Indeed, using the Internet and Facebook, you had inflicted a distinct, deliberate and despicable pattern of sexual abuse and intimidation upon all your young victims,'' he said.