A curate is taking legal action to force police to investigate a late abortion on a woman who did not want to have a baby with a cleft palate.

Joanna Jepson is taking Paul West, chief constable of West Mercia police, to court because she says he sanctioned an illegal abortion by failing to investigate a pregnancy termination after the six month legal limit.

An unnamed woman chose to abort the foetus after finding out it would be born with a cleft lip and palate - although the pregnancy was past 24 weeks. After this time an abortion can only be carried out if there is a risk of serious handicap.

Miss Jepson, 27, curate of St Michael's church, Chester, believes a cleft palate is not a serious handicap. The curate, who had corrective surgery for a congenital jaw defect as a teenager, wants the law to prevent late abortions for trivial reasons. Her original application for a judicial review was rejected, but she is renewing the appeal. Oral arguments will be heard next month.

"I do not understand how a cleft palate can be classed as a serious handicap," she said. "This case raises the increasingly worrying concern of eugenics in our society."

Miss Jepson, who does not belong to any anti-abortion group, says she does not intend taking the mother to court. The action is being funded by private donors.

West Mercia police said the chief constable could not comment as legal proceedings were ongoing. But in papers submitted to the high court, Mr West claims detectives acted on the advice of Heather Mellows, vice-president of the Royal College of Obstetricians and Gynaecologists.

The chief executive of the British Pregnancy Advisory Service, Anne Furedi, said: "When the law was passed it was deliberately left vague for the decision to be made between the woman and her doctors. We feel that this is appropriate. Clearly it is the case that what some people regard as extremely serious, others would feel differently about."