A man who started molesting his biological daughter when she was nine, and repeatedly raped her after she turned 11, was found out after he tried to feed her contraceptive pills.

He had disguised the pills as cough medication.

The girl told her mother about the pills, and when the woman confronted her husband, he confessed that he was worried about getting the girl pregnant.

Yesterday, the 45-year-old was sentenced to 21 years' jail and 24 strokes of the cane by the High Court after he pleaded guilty to two charges of statutory rape and one charge of sexual assault by penetration.

Judicial Commissioner Philip Jeyaretnam accepted the submissions of the prosecutor and defence counsel, who had both sought the sentence based on sentencing frameworks for both offences.

The judge noted that the man had abused his parental authority and betrayed his daughter's trust, and planned his offences when his wife was less likely to catch him.

However, he also took into account that the man had immediately confessed and pleaded guilty, sparing his daughter from having to testify.

The judge added that he hoped "time will do some healing to the family you have fractured".

Another eight charges for various sexual offences were taken into consideration.

The man cannot be named due to a gag order to protect the identity of the victim, who is now 14 years old.

The court heard that the man and his wife married in China in 2007 and emigrated to Singapore in 2008. They obtained permanent residency a year later and the girl moved here in 2010. The man has since obtained Singapore citizenship.

The family, including the victim's younger brother, lived in a four-room Tampines flat, but usually slept in one bedroom.

In 2017, the man began touching his daughter inappropriately, and then moved on to more intrusive acts.

The assaults took place at least once a month, either at night or on Saturday mornings, when the victim's mother was at work.

After the girl realised from sexual education lessons that what her father was doing was wrong, she would resist his advances, but her attempts were futile.

He started raping her after her 11th birthday and told her not to tell anyone about it.

After he had unprotected sex with her on March 12, 2019, he went online and bought a box of contraceptive pills.

He then put the pills in a small resealable bag from a clinic that stated "for cough" on the label.

On March 14, he told the girl to consume the pills but refused to tell her what they were for. She then told her mother about it, retrieved the pills and saw the label.

"As the victim did not have a cough, she knew that the pills were not for cough," said Deputy Public Prosecutor Eugene Lee.

After confronting her husband, the woman lodged a police report the next day.

Yesterday, the man's lawyers, Mr Jonathan Wong and Mr Riko Isaac, submitted letters from his wife and daughter pleading for leniency.

"We are instructed that his wife and daughter have found it within their hearts to not only forgive our client but also take active steps to reconcile with him," said Mr Wong.