The child was finally found huddled inside a flat with her mother, surrounded by bin bags full of rotting food.

One social worker said conditions were so bad, she expected to find everyone dead.

The girl, who had missed two-thirds of her days at school, said later she had been sexually abused by the husband of one of her mother's friends, who had been used as an unregistered childminder.

The city council agreed to pay £8,000 compensation to the child and her father after the Local Government Ombudsman, Pat Thomas, found it had committed maladministration "of a most serious kind".

She concluded that council officers failed to investigate because they thought the complaints by the dad - who was separated from the girl's mother - was typical of a custody dispute.

The girl's father, identified in her report as a "Mr Carrick" - all the names given in the report are fictitious - had moved to London after separating from her mother. The mum and her child - referred to as "Louise" - still lived in Manchester.

Mr Carrick alerted social services in December 1996 when he found no-one at home at the flat, but discovered plates covered with fungus.

The mum failed to turn up for a discussion about Louise's care and the case was closed.

Mr Carrick complained a second time in January 1997, but the case was closed again when a social worker failed to get into the flat. Another visit was arranged in September 1997, but again there was no one at home and the file was closed.

In January 1998, social services and police went to Louise's school and met with her mother, called "Ms Chant" in the report. They agreed to visit her flat in three days' time and found it clean and tidy.

Meanwhile, education welfare officers were worried about Louise's poor attendance at her new school.

They tried to visit Ms Chant and sent warning letters, but did not get any response and in December 1998, they spoke to social services. It emerged Louise had been at school on only 41 out of a possible 134 days.

Then in January 1999, police and social workers found Ms Chant and her partner huddled up with Louise - who was then aged five - in one room of their flat. Louise told welfare officers she could not remember when she had last eaten.

She was later interviewed by social services and said she had been sexually abused by the husband of her mother's friend.

He was prosecuted, but not convicted. The Criminal Injuries Compensation Authority later ruled that on the balance of probabilities, Louise had been the victim of a crime. She was awarded £3,300.

Mr Carrick complained to Manchester city council, which admitted that on all but the last occasion when he had warned them about Louise, they had closed the case without any contact with the girl.

The council confirmed the flat was unacceptable, but argued it was impossible to say whether the sexual abuse could have been avoided in any circumstances.

Ms Thomas said Louise had been found in "conditions of unspeakable filth and neglect" and added: "Louise would have been removed from the care of her mother two years earlier if the council had properly followed up referrals made to it."

Pauline Newman, the council's director of children, families and social care, said: "We regret the poor practice and would wish to apologise to her and her father."