A decision to lift the ban on using frozen human eggs could help thousands of women - including those delaying motherhood for career reasons.

The clinic which has won the right to thaw and use the eggs for IVF already holds eggs from 10 women who have chosen to freeze them for "social" purposes.

However, most of those likely to benefit immediately have stored eggs before undergoing cancer treatment likely to make them sterile.

A-level student Joanne Sprawson, 17, from Faversham, Kent, was diagnosed with breast cancer in October and told that chemotherapy might make her infertile.

She said: "I'm very young and didn't think much about having kids before I was told I had cancer.

"But when they said I might be made infertile, I thought, oh God, because I love children so much and want to have them when I'm older, in my 20s or 30s.

The ruling, by the Human Fertilisation and Embryology Authority (HFEA), represents a victory for a vigorous campaign by fertility clinics and women whose eggs are stored there.

While there is no restriction on using the technique to help women who wish to delay motherhood for career reasons, guidelines on the use of donated eggs, published last week, said that doctors should consider the relative risks to mother and child of pregnancy at a later age before going ahead.

Despite the technique being widely-used abroad, with up to 50 babies born in the US alone, the HFEA had previously considered it too risky - but now an independent report says it is safe.

Carolyn Neill can now go ahead with treatment

The Assisted Reproduction and Gynaecology Centre in London now holds the only licence for thawing and using the eggs.

Its director, Dr Mohamed Taranissi, said: "It will give them hope and give them a positive focus at a very difficult time in their life - because they can see the light at the end of the tunnel."

The decision to lift the ban was prompted by an independent report commissioned from Dr Sharon Paynter, lecturer in obstetrics and gynaecology at the University of Wales, Cardiff.

She said that while the technique did carry risks, results abroad had been "very encouraging".

'Always sympathetic'

In a statement, the HFEA's chairman Ruth Deech said: "The HFEA has always been sympathetic to the plight of women suffering a serious illness, such as cancer, whose condition or treatment may prevent them producing eggs, but we must guard against any potential risks to any child who may be born.

She told the BBC that the HFEA was confident that once babies were born, they would be healthy.

She said: "Many of the eggs do not survive the freezing process, many do not survive the thawing process, so many get lost along the way."

Prior to this ruling, clinics in this country have been licensed to freeze and store the eggs, but not to thaw and use them.

The BBC highlighted the case of Carolyn Neill, from Belfast, who now wants to start a family but was told she cannot even take her frozen eggs abroad to a country which permits the procedure.

She and the Assisted Reproduction and Gynaecology Centre in London, were threatening to launch a judicial review of the decision - but now she will be able to go ahead with the treatment.

She told the BBC: "The cancer is gone - the chemotherapy has taken everything, but I froze the eggs so that I would still be able to have a family."

She has nine eggs stored at the clinic, and at least 50 other women are understood to have eggs stored there.

However, the use of frozen eggs carries a much lower success rate than conventional IVF, between 1% and 10% as opposed to approximately 20% for normal IVF.