"Yes, one of them ended up pregnant." But outside parliament, the opposition said it was not known whether Hall was responsible for the alleged pregnancy or whether the father was another man awaiting gender reassignment surgery in the same wing.

Independent upper house MP Peter Breen demanded to know if any inmates had fallen pregnant to Hall while he was held at Mulawa. But the Department of Corrective Services said there was no evidence that Hall had impregnated a female prisoner. "We have nothing in our records to suggest that has occurred," a spokesman said.

Hall is serving a maximum 22-year sentence for the murder of hitchhiker Lyn Saunders in 1987. The government unsuccessfully challenged a decision granting her parole in July, but the parole order was later revoked because Hall's post-release accommodation became unavailable.

The State Parole Authority (SPA) today confirmed the revocation order, meaning Hall will spend at least another 15 months behind bars. The prisoner, who was known as Noel Crompton Hall before having sex change surgery in 2003, was held at the Mulawa women's prison for eight months over 1999 and 2000 before being transferred to Long Bay jail. She has been accused, but not convicted, of sexually assaulting other prisoners at Mulawa.

In 2004 she was put into segregation following an inmate's complaint, which was subsequently withdrawn. Justice Minister Tony Kelly said he did not know how many male inmates had been housed at Mulawa prior to them undergoing sex change procedures.

"In relation to where they're housed, that's done in accordance with the international standards," Minister Kelly told parliament. The parole authority's decision was welcomed by the government and by Marrion Saunders, whose son Lyn was murdered by Hall. Saunders said she was "delighted that sanity has prevailed ... and that this person has not been allowed into your community".

Her 29-year-old son was shot in the back after he failed to find someone who could provide Hall with marijuana. "That didn't kill him, so he turned him over and put the gun in his mouth and pulled the trigger," Ms Saunders said outside the parole hearing.

"This person was going, without rehabilitation, to be put into your community." It is proposed that Hall will undertake a two-year course of treatment in custody - a combination of violent offender and sexual offender programs - to help prepare for her eventual return to society. Her case will not be considered again until December 2007.

Opposition justice spokesman Andrew Humpherson said he doubted Hall would be ready for parole in 15 months' time. "I don't think there should be any reconsideration of parole for this offender until such time as there is no risk to the community," he told reporters.

He said the justice minister should have the power to veto decisions by the SPA to release prisoners, or to force their reconsideration. AAP