A 14-year-old girl's allegation that her biological father had repeatedly raped her was met with disbelief and scorn by her own family, the High Court heard yesterday on the first day of the man's trial.

Her paternal grandmother likened her to women in TV dramas who seduce men, while her mother, in a text message, accused her of framing her father just to get freedom, a counsellor from her former secondary school testified.

The man, a 34-year-old technician, is fighting two charges of raping his daughter, the eldest of his three children, at the family flat in Punggol on Nov 19, 2014 and on Jan 9, 2015. He cannot be named to protect the identity of the girl.

The girl, now 17 and staying at a shelter for teenage girls, alleges she was raped eight times in the two-month period, usually on a Friday when her mother was away for mahjong, she told the counsellor.

Prosecutors have zoomed in on two incidents "which she can most vividly recall" in laying the two charges against the man.

Deputy Public Prosecutor Winston Man told the court the girl will testify that on Nov 19, 2014, her father forced his way into the locked common toilet while she was changing and raped her. Her mother was at work and her father allegedly warned her not to tell anyone what he had done to her.

She will also testify that on the night of Jan 9, 2015, her father grabbed her from behind, took her to her bedroom, and raped her on her bed, said the DPP. Her mother was at a mahjong session.

Her younger siblings were at home during the two incidents.

School officials reported the matter to the police and the Ministry of Social and Family Development after she told the counsellor what her father had done. The man's semen was found on a pair of shorts she was wearing at the time of the second incident, said the DPP.

On April 2, 2015, the man admitted to police that he had sex with his daughter on one occasion. He now alleges that the statement was not made voluntarily.

The girl's allegations surfaced when she told her boyfriend that her father had raped her.

The boy testified yesterday that she agreed to be his girlfriend in December 2014 but he did not see her that month and only chatted with her via a mobile game as her "strict" parents did not let her go out.

When school started the next year, she asked him if he would still like her if she was not a virgin, and he replied that he liked her for who she was, the boy told the court.

On Jan 9, 2015, before school assembly, she broke down as she told the boy her father had raped her. "She kept crying and I lent her my shoulder," he said.

She was reluctant to report the matter as she was worried it will break up the family, but he urged her to report the matter and booked an appointment with the counsellor.

He later found out that she spoke of eight rapes. "I found it very terrifying that her own father could rape her so many times," he said. The couple stopped seeing each other soon after.

When asked if she could be lying, the boy said he believed her. "This is a very serious case. I don't think she will joke about this kind of thing."

If convicted of rape, the man faces up to 20 years' jail, and caning or a fine.