Eggs being held in frozen storage at clinics such as Fertility Associates may now be implanted after being thawed and fertilised.

The move is one of two changes proposed to help infertile cancer sufferers have babies and help treat rare diseases.

And Advisory Committee on Assisted Reproductive Technology (Acart) last year called for public submissions on the practice, which has not been allowed in New Zealand until now.

When the practice was last reviewed in 2005 the use of frozen eggs was considered too risky because of a lack of information surrounding the new technology.

But Acart said the record of cases over the subsequent three years had changed expert opinion, and it was safe to proceed with the treatment.

About 30 people who have frozen eggs - for reasons ranging from cancer treatments, preserving fertility as they age, or because they were more comfortable freezing eggs rather than embryos.

The approval is for people over the age of 20 years.

Fertility Associates's clinical director, Dr Richard Fisher, said the change would give people, including some patients who had had life-threatening illnesses the possibility of becoming parents of their own biological children.

It also offered women - who knew they wanted children but who have not found a partner - the possibility of some choices in the future.

Frozen egg reproductive technology is used in a number of countries around the world.

The chance of pregnancy depends on a number of factors such as the age of the woman at the time she freezes her eggs. Current success rates are lower than conventional IVF but are steadily improving and over 1000 babies have been born from the use of this technology worldwide.