More than one in eight children in well-off countries around the world say they have experienced some form of sexual abuse in their lifetime, Scotland's child abuse inquiry has heard.

Even more - one in five - has been at the receiving end of violence from a parent or caregiver, the inquiry was told.

The hearing heard claims there is a "huge gap" between the cases known about by authorities and what children actually report when they are questioned in a confidential survey.

The evidence emerged on the second day of the public hearing phase of the inquiry in Edinburgh.

The public evidence-gathering sessions in the far-reaching probe got under way on Wednesday with a series of opening statements from a variety of organisations.

More than 60 residential institutions, including several top private schools, are being investigated by the inquiry, chaired by Lady Smith.

Professor Lorraine Radford, of the University of Central Lancashire, carried out a review for the inquiry of various pieces of research on abuse.

Summarising her review of 31 global studies, focusing on "high income" countries, her report stated: "Globally, more than one in eight (12.7 per cent) of children and young people say they have experienced sexual abuse.

"More than one in five (22.6 per cent) say they have experienced physical violence from a parent or caregiver.

"More than one in three say they have experienced emotional abuse from a parent or caregiver.

"Between one in six (16.3 per cent) and one in five (18.4 per cent) children and young people say they have experienced neglect."

During questioning by Colin MacAulay QC, counsel to the inquiry, Prof Radford said: "Despite over 200 years of awareness about child abuse, we know that it's globally still very prevalent and it's very prevalent still in high-income countries."

The witness's research also concluded boys and girls are equally likely to be victims of maltreatment by a parent or caregiver.

However, rates of girls reporting child sexual abuse are typically at least three times higher than the rates reported by boys.

A child's vulnerability can vary with factors such as their age, development, gender and disability, the inquiry heard, and a child abused at home is more likely to be further abused in another setting.

"All of these messages add up to a message that suggests that children in care will be highly vulnerable and in need of extra protection," Prof Radford said.

The inquiry was, however, told about the limitations of the data available, including the lack of recent Scotland-specific figures.

Earlier, the inquiry heard how the state had a "very judgmental" attitude towards children in poverty in the first half of the 20th century.

Professor Kenneth Norrie, of the University of Strathclyde's Law School, told how lawmakers before 1948 sought to "insulate" youngsters from poor or criminal backgrounds from negative influences in order for them to become productive members of society.

This could result in them being removed from their families, with little contact with their parents, the inquiry heard.

The inquiry continues on Friday.