"If a transgender prisoner has a change of gender recorded on their birth certificate they are automatically put into a prison based on that gender.
"In February 2014 the Corrections regulations were amended to make it easier for trans individuals to apply to the chief executive to be placed in a prison that accords with their identified gender."
Court documents listed Seu as a male and throughout Seu's sentencing they used masculine pronouns.
Corrections said since the 2014 amendments, 18 transgender prisoners had applied to transfer prisons.
Of these, 17 had been successful and the outcome of the 18th application was pending, Mr Beales said.
Corrections would not say whether Seu was the 18th prisoner.Seu's lawyer, Sarah Saunderson-Warner, said she could not comment on the case or whether Seu had applied to transfer prisons as Seu had not provided any instruction on discussing such information with the media.
Mr Beales said not all transgender prisoners could apply for such a transfer, but would not say whether that referenced Seu.
"We note that not all trans prisoners choose to apply to have their placement changed and some trans prisoners are ineligible to apply due to the nature of their offending," he said.
"While trans prisoner numbers are very small - approximately 12-20 prisoners in a population of more than 10,000, we recognise the additional challenges transgender people in New Zealand are likely to have faced prior to coming into the criminal justice system and that the prison environment has potential to compound some of those challenges.
"Over the past year Corrections has been working on a new approach to the management of trans prisoners to bring New Zealand into line with international best practice.
"The transgender action plan provides a framework for staff to better plan and enhance trans prisoners' safety, dignity, privacy and their right to maintain their gender identity while in our care," Mr Beales said.
"These guidelines align Corrections' approach with other jurisdictions, including England and Wales, Scotland and some of our Australian counterparts.
"The new approach will require prison staff to put a safe management plan in place for each trans prisoner, which will be completed collaboratively with the prisoner, and reviewed at regular intervals.
"We also contracted a member of the trans community to interview trans prisoners and assist in the development of support systems for trans prisoners.
"Two prisons have trans consultants who conduct support groups and other work with trans prisoners," he said.
Seu, who has a history of violent offending, committed sexual violation of one young male victim. The two other victims were groped and had Seu's bottom rubbed against their groins.
Seu will be at least four years behind bars after being sentenced to a minimum non-parole period.
