A mother of three diagnosed as a pathological liar poses a "grave risk" to her children, a family court judge has ruled.

Mr Justice Keehan said a psychiatrist concluded that the woman, who is in her 20s, suffers from "factitious disorder by proxy" - a condition which can lead to people acting as if someone in their care is ill.

He said she had fabricated symptoms of epilepsy in her four-year-old daughter, falsely claimed that the little girl had been diagnosed with a brain tumour and a peanut allergy - and told nursery staff that medics said the youngster should drink three litres of liquid a day.

Detail of the case emerged in a ruling by Mr Justice Keehan following a hearing in the family division of the High Court in London.

The judge said the girl suffered a fractured arm and puncture wound to her abdomen and a local authority with responsibility for her care asked for rulings on the cause of the injuries.

He said the woman gave seven different explanations for the arm injury and suggested that the puncture wound was caused by a pen.

But he concluded that she was "culpable" for both.

"The mother poses a grave risk of physical, emotional and psychological harm to her children," said Mr Justice Keehan.

"I find it difficult to see how, without some significant change in the mother, that risk can be ameliorated or reduced to a manageable or acceptable level.

"In acting as I have found the mother has, she has failed to act as one would expect of a loving, caring, and protective parent."

The judge said the woman had two other daughters - aged six and three months - who were also the subject of family court proceedings.

He said she suffered an "extremely troubled childhood".

"She was seen by consultant child and adolescent psychiatrists on a number of occasions because of her behaviour," said Mr Justice Keehan.

"She has alleged she was physically and sexually abused by her father."

The judge added: "(A psychiatrist) diagnosed the mother as suffering with factitious disorder by proxy."

He said the psychiatrist had also diagnosed "pathological lying", "emerging borderline personality disorder traits" and "anti-social personality traits".

Mr Justice Keehan said no one involved could be identified.