Image caption The court of appeal in Singapore overturned Zunika Ahmad's controversial acquittal

The highest court in Singapore has jailed a transgender man who is biologically female for the sexual abuse of a 13-year-old girl.

In April, a court ruled the defendant was a woman and issued an acquittal, saying only men could be convicted of penetrative sex with a minor.

But in a landmark judgment, the court of appeal overturned that ruling, saying the law was gender-neutral.

The defendant has now been sentenced to 10 years in jail.

Singaporean media have reported the case as the first time a woman has been convicted of the sexual abuse of a female child.

False identity

According to local news reports, Zunika Ahmad was born female in Singapore but had always identified as male, and in later life assumed the false identity of an Indonesian man.

Under that identity, the defendant had married two women and was also listed as the father of one of their children, who was actually fathered by another man, the court heard.

The women had said they did not know their husband was biologically female, and that when they had sex they were not allowed to touch or see his genitals for "superstitious reasons".

In 2011 Zunika Ahmad befriended a 13-year-old girl who lived nearby, and began to sexually abuse her.

The abuse lasted for two years and only came to light in 2014 when the two had an argument and the girl told her family about their relationship. Her family made a police report and Zunika Ahmad was arrested.

The victim told the Straits Times newspaper that she had no idea that Zunika Ahmad was biologically a woman.

Zunika Ahmad pleaded guilty in December last year to sexual penetration of a minor.

The trial court heard that the defendant had gender dysphoria and identified as male. But a judge said she was biologically female, and that the law applied only to men.

Section 376A of Singapore's Penal Code states it is an offence for "any person (A) who sexually penetrates, with a part of A's body (other than A's penis) or anything else" another person under the age of 16.

The prosecution appealed against that ruling, arguing that the law was meant to be read as gender-neutral.

At Monday's hearing the appeals court agreed, sentencing Zunika Ahmad to 10 years in prison, with the possibility of further convictions for using a forged Indonesian passport and for fraud in birth registration.