SINGAPORE - Despite getting slapped for following a woman into a HDB lift and squeezing her buttocks, Habib Noor Yusoff tailed her all the way to her home in Boon Lay. He stood outside the flat and masturbated in full view of her, even after she had run in and locked the gate.

On Friday, Habib Noor, 25, was jailed eight months for two crimes committed on Aug 7. He pleaded guilty to outraging the modesty of his 24-year-old victim, and doing an obscene act in front of her.

This was even though the man, whose occupation was not mentioned in court, was ordered in 2011 to undergo treatment for committing two obscene acts in public.

There had been an escalation in the level of his wrongdoing, the prosecution said.

The court heard that around 5am that day, Habib Noor had squeezed the woman's buttock as she was walking out of the lift. Shocked, she slapped him and ran towards her unit, noticing that he was pulling down his shorts. Habib Noor then stood outside her gate and continued with the obscene act, ignoring his victim's warning that she would be calling the police.

Habib Noor had left by the time the girl's boyfriend came out to confront him, but the boyfriend and passersby managed to catch him at the void deck. The police were called in and Habib Noor was arrested.

Calling for Habib Noor to be jailed for at least six months, Deputy Public Prosecutor Daphne Lim cited a report from the Institute of Mental Health which said the man was not suffering from any mental disorder. He had clearly not mended his ways despite being previously sentenced to undergo treatment for similar offences, the report said.

Habib Noor also admitted to hurting a man on Dec 5 last year by rashly throwing a plastic chair at him at a coffeeshop.

For using criminal force to outrage his victim's modesty, he could have been jailed for up to two years and fined. For committing an obscene act in a public place, he could have been jailed for up to three months and fined.