SINGAPORE - A serial molester, who had been in and out of jail since 2003, reoffended a month after he was released last year, and while out on bail, molested two 13-year-old girls.

Vaz Clive Hilary Cheng Kiat was released from prison on Jan 19 last year before he outraged the modesty of a 31-year-old woman the following month.

The court heard that he also molested a 24-year-old woman on March 9, 2019.

He was arrested three days later and granted bail.

But Cheng could not keep out of trouble as he went on to molest the two teenage girls in separate incidents on buses.

The 41-year-old Singaporean pleaded guilty on Monday (Sept 14) to two molestation charges involving the teenagers.

Two other charges for similar offences linked to the women will be considered during sentencing.

On May 25 last year, one of the teenage girls boarded bus service 190 with her younger sister and their parents near Clarke Quay Central shopping mall at around 8pm.

They went to the upper deck of the bus where the girl sat beside her sister, while their parents took the seats in front of them.

Cheng boarded the bus about 20 minutes later and sat behind the two girls although there were many empty seats on the upper deck.

He molested the 13-year-old girl through a gap between the seat and a window.

Even though her parents were nearby, the teenager kept silent as she was afraid and did not know how to react.

She told her mother about what had happened only after they alighted near Ion Orchard shopping mall later that evening.

Cheng struck again on Aug 3 this year and targeted another 13-year-old girl, who was on her way home from school.

They were sitting at the upper deck of bus service 43 at around 2.45pm that day when he molested her.

The girl yelled at Cheng, who immediately raised both palms and apologised before getting up.

She asked another man seated nearby for help, but he refused and told her to inform the bus driver instead.

After the girl told the driver, Cheng denied molesting her when confronted.

The driver pulled up at a nearby bus stop near Asiawide Industrial Building in Pereira Road, off Upper Paya Lebar Road, closed the doors of the bus and told Cheng to take a seat.

When a passenger wanted to alight, the driver opened the doors.

Cheng then took the opportunity to run out and the passenger chased after him.

He grabbed Cheng's bag during the pursuit, causing the offender to fall down and fracture his knee cap.

The driver alerted the police and Cheng was taken to Tan Tock Seng Hospital for treatment.

On Monday, Deputy Public Prosecutor Chong Kee En said: "When interviewed... (the girl) stated she was 'very shaken', 'very traumatised and scared' and 'very outraged'.

"She blamed herself for 'not doing better when the incident happened, like scream or fight back'. She did not wish to take buses any more."

Cheng will be sentenced on Sept 18.

For each count of molesting a girl below 14 years old, an offender can be jailed for up to five years and fined or caned.