When Dawn Thwaite had embryos put on ice in 2000, she never suspected her husband would prevent her from using them.

Mrs Thwaite went through three cycles of IVF fertility treatment from 1995 to 2000 at the Fertility Centre, which left her depressed, but not pregnant. It also left her with four frozen embryos and a bitter dispute. The couple, who lived in the South Island, separated in 2006, three years after they had adopted a baby girl, now 6.

Aged 39 and now a school bus driver in Dargaville, Mrs Thwaite wants to try again to become pregnant using the stored embryos.

But despite having at first agreed, her former partner withdrew consent; he will also not permit the embryos to be donated to another couple.

"He will only consent to them being used for medical research, which I absolutely will not consent to," said Mrs Thwaite, who was raised a Catholic. "They are precious little lives with nobody to speak for them but me."

"I will not consent to them being destroyed or used as guinea pigs, so that means they will stay in storage indefinitely."

Research on viable embryos left over after IVF (in-vitro fertilisation) treatment is not permitted. But a high-level Government-appointed committee has advised Health Minister Tony Ryall he should allow it.

The committee said many submissions supported the concept if the parents gave informed consent and the research was potentially beneficial to human health. Mr Ryall is still considering his response.

Mrs Thwaite's former partner said that after his new partner became pregnant he withdrew his consent for Mrs Thwaite to use the stored embryos because if she had a child as a result, it would be outside his own family and he would bear a financial responsibility for it.

"She has moved so far away that I couldn't be a father to the baby if it was ever born. I'm only seeing my daughter twice a year as it is."

Dr Peter Benny, medical director of Repromed, formerly called the Fertility Centre, said embryos created by IVF were jointly owned by a couple.

The Christchurch clinic made it clear from the outset that stored embryos would be thawed and implanted only with the consent of the woman and the man.

Family law specialist Margaret Casey said no fertility clinic would implant embryos without the man's consent, because it created a binding legal and financial liability if a child was born.

THE LAW

* "Surplus" viable embryos from in-vitro fertility treatment, no longer wanted by the couple who created them, can be donated to other couples for implantation.
* Or they can be discarded.
* They cannot be used for medical research, but the Minister of Health is considering a recommendation to permit this use.