The teacher, who has name suppression, pleaded guilty in the North Shore District Court in 2009 to eight charges of indecent assault on a 15-year-old girl. The offending occurred in 1991.
He is teaching girls of the same age but a court order prevents the school being identified.
The Teachers Council has put conditions on the man's employment but has refused to say what they are.
The victim's mother - who has not been named to protect her daughter's identity - says nothing in the ministerial inquiry's recommendations stops schools from employing sex offenders as teachers if they want to.
"Does another child have to go through what my daughter had to go through? Does someone else have to live with this?"
No law prevents convicted sex offenders from working, but the Teachers Council can place strict conditions on teachers with such convictions.
There is one paragraph in the 130-page ministerial report relating to the teacher at the private school.
Former Education Review Office chief executive Dr Judith Aitken and former ombudsman Mel Smith, who conducted the inquiry, found the Education Ministry had insufficient evidence to confirm the teacher was a risk to children.
The report said the ministry had no "basis for assessing the level of risk in other cases of sex offenders retaining their registration".
It recommended a review of legislation and policies on the amount of discretion available to schools.
Ms Parata was asked what assurances she could give to parents and children.
She said it was boards of trustees' responsibility to make assurances to its parents and children.
"If parents have concerns, they should make them known to the board."
The board which employed the convicted teacher in Auckland knew the circumstances when it hired him, and his registration had been considered by the complaints assessment committee of the Teachers Council, which agreed he could be registered subject to conditions.
Asked if people could have faith in the registration system, Ms Parata said she wanted to assure parents that changes and "extra vigilance" would stop people like Miki getting work.
Corrections Minister Anne Tolley said a complicated law change would be needed if the Department of Corrections and the Education Ministry were to make criminal background checks compulsory for all staff teaching in schools.
Mrs Tolley said schools required signed consent from a would-be employee before a full police check could be made.
"Alarm bells should be ringing for any principal or board of trustees who employ a teacher not prepared to sign a consent for a police check," she said.
Mrs Tolley said she was confident the Corrections department acted properly in the Miki case.
"We are dealing with a highly manipulative person, but it's been a good opportunity to look at the Corrections system and say ... how can we tighten up some processes."
How Miki's web of deception beat checks
Henry Te Rito Miki used three names as part of a "complex web of deceit" to evade checks and work in classrooms - despite a conviction for sex offending.
* Miki produced a fake CV and birth certificate after assuming the identity of a registered teacher who had moved to Australia.
* He was able to evade authorities for five years while he was under an extended supervision order after being jailed for an indecent assault on a 14-year-old boy.
* The order prevented him from working as a teacher or associating with children under 16.
* In 2009, Miki was arrested by Tauranga police and was removed from the grounds where he was working.
* The report found: "The principal erroneously assumed that this information would get to the Teachers Council via the police. She could recall nothing in her induction programme that emphasised mandatory reporting, and certainly her employer had given her no directions or advice on this matter either before or after Miki's arrest".
* He was charged with breaching release conditions and sentenced to 125 hours of community service.
He was able to quickly secure another teaching position.
* Miki is now in jail for four years after pleading guilty to seven charges of fraud and four charges of breaching a supervision order.
Official response
* The Government responded with measures to better share information, and tougher employment checks.
* The report made 35 recommendations, which have been split into 39 actions.
* Ms Parata said 26 of these had been accepted and seven were completed. Three were being considered.
* The ministry is considering biometric photographs of all teachers in order to verify their identity.
* Boards of trustees had been issued with reminders on the process of hiring teachers and support staff.
* Eleven recommendations related to the Teachers Council, which is under review. A report will be issued in October.
