By Kate Kelland

LONDON, Dec 2 (Reuters) - A young British curate leading a legal battle over the abortion of a baby with a facial disfigurement said she was determined to fight a culture of perfection which is driving society towards eugenic-style human selection.

Joanna Jepson, a 27-year-old clergywoman, was horrified to learn of a case where a woman was granted a late-term abortion because the foetus was found to have a cleft lip and palate.

She has taken the case to the High Court, where she hopes to persuade judges the abortion was an unlawful killing of a baby driven by an obsession with what you look like, not who you are.

"This is about our enslavement to physical perfection," said Jepson, who was herself born with a facial disfigurement later corrected by surgery.

"That cannot be allowed to become a determining factor in life," she told Reuters in an interview on Tuesday. "That's what eugenics is about -- selecting those we want and disposing of those we don't want."

The case -- in which the date of the abortion and the identity of the mother cannot be revealed for legal reasons -- has sparked a furious row between anti-abortion campaigners, medical ethics specialists and pro-choice campaigners.

Richard Nicholson, editor of the respected Bulletin of Medical Ethics, has little doubt the abortion was illegal under the 1967 Abortion Act, which allows termination after 24 weeks only in cases where a baby may have a serious handicap.

"From what I know of the case -- that it was a case of cleft lip and palate -- I would argue this was not what parliament intended and was therefore unlawful."

The case is likely to come before judges early next year and is one which experts say will expose British abortion law to some deep and potentially far-reaching scrutiny.

Pro-choice campaigners are furious that Jepson has been able to intervene in a case which they see as a private matter between the mother and her doctors.

A spokeswoman for the British Pregnancy Advisory Service told Reuters the legislation had been "deliberately left vague for the decision to be made between the woman and her doctors."

She said the abortion of the cleft palate foetus was "wise and humane" and strongly objected to the legal challenge.

But for Jepson and her supporters, the case is not so much about the rights or wrongs of abortion, but about the risk of a slide toward eugenics -- which Jepson points out was a form of selective breeding supported by the Nazis.

"The age of the supermodel is here -- it seems everyone has to be perfect to be accepted," Gareth Davies, chief executive of Britain's cleft lip and palate association told Reuters. "The idea that because someone doesn't look quite right or sound quite right they should be terminated is outrageous."

Jepson, who works as a curate in the town of Chester, northwest England, says her own experiences as a child with severe jaw abnormalities underline her determination to win the case.

Born with an upper jaw which protruded extensively over the lower one, she spent years never being able close her mouth and was often the victim of teasing.

Corrective surgery at the age of 17 and again at 19 solved her problem, but she insists it was not beauty she wanted, rather simply the ability to eat, drink and communicate more easily.

"What is it that is shaping society to say we should dispose of a baby who doesn't conform to an external standard of perfection?" she says. "If we put this much emphasis on the external, we are actually losing sight of the real substance of our human identity."