Children in care should have access to independent help and advice to prevent child abuse cases from remaining hidden, the government has been told.

The call comes from a group of organisations, including the NSPCC and ChildLine, on the eve of the publication of a report into Britain's worst child abuse scandal.

The government is expected to publish the Waterhouse report into abuse in north Wales children's homes later this week.

The 18-month inquiry, headed by Sir Ronald Waterhouse QC, covers the alleged abuse of up to 750 children in 40 homes over two decades.

The report is expected to contain widespread criticism of social services and North Wales police.

Widespread abuse

Among the damming evidence is that the Welsh social services inspectorate only checked five residential homes throughout Wales in seven years.

Last year, a member of the inspection team was jailed for 14 years for indecently assaulting children.

The inquiry heard allegations against 148 people in 40 homes, centring on the former counties of Gwynedd and Clwyd.

Sexual and physical abuse

More than 200 complaints of sexual and physical abuse were made at the Bryn Estyn residential care home.

At the privately-run Bryn Alyn children's home, owner Peter Allen was jailed for six years for sexually abusing children in his care.Former care worker Stephen Norris was jailed for seven years for sexual offences.

An independent advocacy service could have prevented many of these cases, child experts believe.

NSPCC child protection director Neil Hunt said: "The tragic and disturbing facts about past abuse in North Wales children's homes were that the children had no one to turn to for help and, when they tried to speak out, they were ignored.

Advocacy services

"If these children had had access to advocacy services to stick up for them, this tragedy might well have been averted," he said.

A spokeswoman for the Department of Health said it would be inappropriate to comment before the Waterhouse report - and the government's response - was published.

The call for advocacy services has the backing of the Boys and Girls Welfare Society, ChildLine, the Children's Rights Alliance for England, Children's Rights Officers and Advocates, the NSPCC, the National Youth Advisory Service and Voice for the Child in Care.