Police investigations in Scotland of alleged child abuse cases involving a number of victims and multiple accused have so far resulted in 21 referrals to the procurator fiscal.

The nature of the alleged crimes and the fact that a "significant proportion" of the perpetrators identified are from an ethnic minority background has led to comparisons with the scandal exposed in Rotherham last week.

A team led by Scotland's former chief inspector of social work Professor Alexis Jay reported that more than 1,400 children had been abused in the Yorkshire town, and that authorities including the police had failed to intervene despite knowing about wide-ranging sexual exploitation.

In Scotland two investigations have been running into the abuse of vulnerable children in and around Glasgow. Operation Cotswold, set up in 2011 was later subsumed into Operation Dash. Several of the inquiries have already resulted in live cases.

The charity Barnardo's has been working with police to bring cases to court. Some of the young people did not see themselves as victims, and police have attempted to disrupt the activities of alleged perpetrators instead.

Martin Crewe, Barnardo's Scotland director, said the Crown Office and Procurator Fiscal Service had concerns some witnesses lacked credibility, or would not do well under cross examination. "We should look at the system and how we can make the evidence-gathering from vulnerable witnesses better," he said.

Shadow UK Home ­Secretary Yvette Cooper yesterday said the law should change to make it an offence to fail to report allegations of child abuse.