The former principal of an ultra-orthodox Jewish school in Australia went on trial Wednesday over charges she sexually assaulted three female students.

Malka Leifer, 56, has been charged with 29 offences stemming from her time as the principal of the Adass Israel School in Melbourne, according to an indictment released by the court.

The school is part of an ultra-orthodox Jewish sect in Melbourne known for its reclusive nature.

The charges, stretching from 2003 to 2007, included raping a student during a school camp, and sexually assaulting another girl inside a school office.

Leifer, a mother-of-eight who left Israel in 2001 to teach at the school, has pleaded not guilty to each charge.

According to the indictment, Leifer raped one student after asking her to "sleep over for kallah lessons" -- a kind of pre-wedding etiquette class that includes sexual education.

On other occasions Leifer told the students she was preparing them to be wives, prosecutor Justin Lewis told the court in his opening statement.

"This will help you for your wedding night," Leifer allegedly said after one sexual assault.

Lewis told the court the three students grew up in a sheltered, conservative Jewish community and were scared to raise the alarm about Leifer, who was a highly respected teacher.

Defence lawyer Ian Hill said Leifer denied "all of the criminal conduct alleged by each of the complainants" and that her interactions with the students were "professional and proper".

"We deny that they are telling the truth," he said.

Australia has strict laws surrounding the reporting of sexual assault, and some details of the case have been suppressed.