SINGAPORE - A full-time national serviceman who had sex with two underage girls was sentenced to 18 months' supervised probation and 150 hours of community service on Wednesday.

Timothy Ong, now 20, had sex with two 13-year-olds between 2011 and 2013.

He was ordered to stay indoors between 10pm and 6am and his parents, who were both in court, also paid a bond of $5,000 to ensure his good behaviour.

In 2011, when Ong was still studying, he had sex with a secondary school student in the bedroom of his house near Upper Bukit Timah Road after meeting her through an online game. They also had sex on one other occasion.

He met the other girl in September 2013 in a similar fashion and they had sex several times over the following months.

The second girl saw messages from the other girl on his mobile and contacted her.

The first girl later told her auntie what had happened and she told the girl's father. He made a police report in May last year. The second victim also made a police report.

Sex with a girl under 16 is a crime even if she gives her consent.

District Judge Mathew Joseph told Ong that the court was prepared to give him a second chance as he was "young and of an impressionable age" when he committed the offences.

Asked if he had anything to say, Ong told him: "I'm sorry for letting my parents down."