Surgeons have begun a lengthy operation to separate Siamese twins whose fate has been the subject of a lengthy legal battle.

Surgeons have begun a lengthy operation to separate Siamese twins whose fate has been the subject of a lengthy legal battle.

The procedure, which will mean life for one baby and death for the other, is being carried out at St Mary's Hospital in Manchester.

A team of 20 staff are involved in the complex operation, which could take until tonight to complete.

The girls, identified publicly only as "Mary" and "Jodie," were joined at the lower abdomen when born on August 8.

Doctors say surgery could allow Jodie to have a normal life, but that Mary would not survive.

If the girls were not separated, doctors said, they would both die within months.

The twins' parents - identified only as Roman Catholics from the Maltese island of Gozo in the Mediterranean - decided not to contest a September decision by the Court of Appeal that the girls can be separated.

A late appeal by the Pro-Life Alliance, an anti-abortion group which wanted the case to be decided in the House of Lords, was rejected by a judge on Friday.

A spokesman for ProLife Alliance, who failed in two court attempts to halt the surgery, claimed Mary's life was being extinguished because she was mentally impaired.

A spokesman said: "These are very sad times for English law and English medicine."

On Friday, the High Court and then the Court of Appeal rejected an application to have Official Solicitor Laurence Oates removed as Mary's legal guardian and replaced by the Alliance's director, Bruno Quintaville.

This paved the way for the operation to take place today.

The legal battle to have them separated and save the life of Jodie began shortly after their birth.

Doctors went to the High Court that month and won the right to separate the twins despite the parents' objections.

They are opposed to the operation on religious grounds.

In September they launched a privately funded appeal against the High Court decision which they subsequently lost.

The twins are joined at the abdomen with arms and legs at right angles to their conjoined upper bodies.

Their spines are fused.

Mary is described as having "primitive brain" functions while Jodie is thought to have normal mental functions.

Mary is draining the life from her sister as she relies on her for oxygen and blood circulation.

It has been reported that their parents have agreed a deal with Granada TV to appear on Tonight with Trevor McDonald.

Money they are paid for their interview will be put into a trust to pay for Jodie's medical care once she has been separated from her twin.

In the UK only St Mary's and Great Ormond Street Hospital for Children in London have any experience at separating Siamese twins.

Great Ormond Street's team has performed the operation on 17 sets of twins. St Mary's has separated just two sets.

A ProLife Alliance spokesman added: "The right to exhaust all legal defence avenues would not be withheld from a criminal on death row anywhere in the democratic world, but has been withheld in the Courts of 'Great' Britain from an innocent child.

"Mary's life is being extinguished not because she is a conjoined twin, not because her heart beats inadequately, not because Jodie's life is under threat, but because she is mentally impaired and her life is deemed of no intrinsic value.

"This tragic case is justifiably causing great distress to disability groups in this country and worldwide.

"Many attribute the starting point of the Nazi programme of euthanasia to the deliberate killing of an infant boy, 'a child which had been born blind, an idiot - at least it seemed to be an idiot - and it lacked one leg and part of an arm."'