A delivery driver, who made his niece perform sex acts on him from around the age of five, was jailed for 6 1/2 years yesterday after a court heard how she and her sister kept the abuse a secret, fearing nobody would believe them because they were only children.

The man, now 29, had been living with the two girls, their mother and grandmother in a Toa Payoh flat when the offences took place between 2006 and 2007. The girl's sister, who is a year younger, found out what was happening when she witnessed her sister being abused.

When they told their grandmother, she scolded them, and they kept it to themselves for seven years. By that time, they had another sister, aged three, and the second sister told a teacher for fear that the child may also end up being abused.

The man pleaded guilty to two charges of making his oldest niece perform oral sex on him and one of making her perform another sex act on him. Four other similar charges were taken into consideration.

None of the parties can be named for legal reasons.

The High Court heard that in 2006, the man, who did not have a job then, was the girls' primary caregiver when their mother and grandmother were at work. The girls' father did not live with them.

After coming home from school each day, the older girl would put her sister to sleep before taking a nap herself.

One afternoon, when the younger girl was asleep, the man called the older girl into his room and taught her how to massage him. He later got her to perform oral sex.

One day in 2007, the girl was summoned to the man's room. By now, she knew what he wanted her to do.

She noticed her sister watching them through a gap in the door, but continued with the act as she feared angering her uncle.

The two sisters then watched TV in the living room as if nothing had happened. A few months later, the younger girl told her sister that she saw what they were doing.

Last year, when the younger girl was 11, she told a teacher that she had skipped school because she was worried about her youngest sister. Questioned further, she revealed what she had witnessed.

The man was arrested five days later, after the victim confirmed she was sexually abused.

A psychiatric report on the victim said she blamed herself for allowing him to commit the acts and has a phobia of men.

Deputy Public Prosecutor Nicholas Lai sought at least six to eight years' jail for the "abhorrent and unspeakable acts".

The man's lawyer Ismail Hamid said he has kept a clean slate since his arrest and joined a grassroots organisation to be a useful citizen.