USA:  A mother has launched a legal battle to gain possession of her dead daughter's frozen eggs so that she can become pregnant with her own child - a case which experts believe is "a world first".

The woman, 59, and her 58-year-old husband are challenging a refusal made by an independent regulator to allow them to take the eggs to a fertility treatment clinic in the US.

The parents claim that they are only trying to carry out their daughter's dying wish.

Their daughter - the couple's only child - died of bowel cancer in her late 20s, and her dying wish was for her eggs to be fertilised by donor sperm and implanted into her own mother's womb.

The daughter initially had her eggs frozen after being diagnosed with cancer in the hope that she herself could have children in the future, but lost her battle for life.

Her parents want to export the eggs to New York, where a clinic has indicated it is willing to provide fertility treatment at an estimated cost of up to £60,000.

There are only a handful of cases worldwide in which a woman has become a surrogate for her own daughter's child.

Fertility expert Dr Mohammed Taranissi, who runs the ARGC clinic in London, said: "I have never heard of a surrogacy case involving a mother and her dead daughter's eggs.

"It's fair to say that this may be a world first."

But the Human Fertilisation and Embryology Authority (HFEA) has refused to issue a "special direction" allowing the eggs to be removed from storage in London and sent to the US.

The HFEA's statutory approvals committee (SAC) made the 2014 refusal decisions saying there was insufficient evidence to show that the daughter wanted her mother to use donor sperm to carry her child.

The committee argues there was no clear, written consent and it was entitled to use its discretion to refuse to issue a special direction, without which it would be unlawful for export of the eggs to go ahead.

Women who have gone through the menopause are still able to bear children using donor eggs and sperm, though obstetricians warn the risks associated with pregnancy, such as miscarriage, are greater.

The application for judicial review is listed anonymously as "M v the HFEA" and it is understood that the family wishes its identity kept secret.

Document already in the public domain reveal the couple's daughter was diagnosed with bowel cancer at 23 and chose to freeze and store three of her eggs at IVF Hammersmith in West London in 2008.

She completed a form which gave consent for the eggs to be stored for use after her death, but crucially, failed to fill in a separate form which indicated how she wished the eggs to be used. This technically meant her consent became invalid.

She died in 2011 without leaving further instructions. She was single. SAC minutes reveal the "strongest and only evidence" of her wishes was a reported conversation with her mother while she was in hospital in 2010.

The young woman is said to have asked an unnamed doctor whether someone with a stoma such as herself could carry a child. The doctor confirmed it was possible.

But, the mother says, it was then agreed that if her daughter could not carry a child "I would do it for her". The minutes say the young woman wanted her mother to "carry her babies... in the context of her not expecting to leave hospital alive".

The couple approached fertility clinics after their daughter died. They hoped to create embryos using standard IVF treatment from their daughter's eggs and sperm from an anonymous donor. However, no UK clinics were prepared to carry it out.

Generally, fertility clinics will not treat women over 50 because of the limited chances of success and the extra risks involved.

The application for permission to export the sperm was made to the HFEA by IVF Hammersmith, which is is based within Hammersmith Hospital in West London and currently storing the eggs.