Jail officials are reviewing accommodation arrangements for transgender prisoners, who for now won't have to share cells with non-trans inmates.

The Department of Corrections confirmed the move in an Official Information Act response about arrangements for transgender inmates.

Since introducing the controversial double-bunking policy in 2010, trans prisoners have been forced to share cells with other inmates.

This and sending trans prisoners to jails based on the gender specified on their birth certificates has come under heavy fire from rights groups.

READ MORE: Transgender woman alleges rape in men's prison

But Corrections has now started looking at its shared accommodation cell risk assessment.

"While the review is under way, transgender prisoners are not to be double-bunked with non-transgender prisoners.

"Transgender prisoners may be considered for placement in a shared cell with another transgender prisoner of the same self-identified gender, subject to their consent."

Presently, there are two transgender prisoners double-bunked with each other, while two were in double-bunked cells by themselves.

Prison officials have also revealed that in 2015/16, they approved 17 transfers for trans inmates from men's to women's prisons. They had 18 requests for such moves.

No transfers were made from women's to men's prisons.

New rules were introduced in February 2014 to establish whether transgender or intersex prisoners should be in a male or female prison, Corrections says.

Before a transfer could happen a prisoner had to get their birth certificate changed to record a different gender from their one at birth.

Prisoners who couldn't change their birth certificates could still apply to Corrections' chief executive for a prison move.

Officials would then consider a range of factors, including the prisoner's commitment to living as a member of that gender and the safety of that prisoner and others, according to Corrections.

A prisoner locked up over serious sexual offence against a person of their nominated gender would not be eligible.

Corrections director of offender health Bronwyn Donaldson said each prisoner was assessed individually to ensure the most appropriate placement.

She said inmates were initially placed based on court documents that specify which jail the prisoner should be sent to.

"If a prisoner has a change of gender recorded on their birth certificate they are automatically put into a prison based on that gender.

"When a prisoner expresses concern for their safety, the department has a duty to ensure that prisoners are housed safely and securely.

"As with any other prisoner, transgender prisoners can apply for voluntary segregation, away from the general prison population, if they have any personal safety concerns.

"Prisoners on voluntary segregation are usually able to mix freely with other voluntary segregated prisoners."

However, rights group No Pride in Prison says on its website that, according a 2007 study in the United States, trans women in men's prisons were 13 times more likely to be sexually assaulted than the men they are imprisoned with.

In April 2016, police and Corrections investigated rape allegations made by a transgender woman inmate at Whanganui Prison. She later admitted making a false statement to police.

A spokeswoman for Corrections said the prisoner was sentenced to one month and 14 days' imprisonment after pleading guilty in the Whanganui District Court.

"This prisoner made numerous allegations against staff, and these were referred to police.

"Corrections has also investigated and found no substance to the allegations. CCTV footage did not back up the prisoner's allegations."

Emilie Rakete, from No Pride in Prison, said at the time the woman, who was locked up in a men's prison, should be in a prison appropriate to her gender.

"Trans women incarcerated in men's prisons are, from the outset, put at considerable risk of assault and rape."