A British inquiry has been told of "the great wrong" done to children sent from the UK to Australian farm schools where they were sexually abused.
The long-awaited inquiry into the historical sexual abuse of children in Britain has started holding public hearings.
It was set up after the death of Jimmy Savile in 2011 when hundreds of people came forward to say he had abused them as children.
It has finally started after a number of delays due to the resignation of several of its chairs, including the New Zealand judge Dame Lowell Goddard.
The former managing director of the Australian Broadcasting Corporation, David Hill, held back tears as told the inquiry many children experienced "unacceptable depravity".
Mr Hill was one of thousands of child migrants sent to Australia and he believes up to 60 percent were sexually abused.
Mr Hill called for perpetrators to be "named and shamed".
Meanwhile the Independent Inquiry into Child Sexual Abuse (IICSA) has apologised and referred itself to the information commissioner after mistakenly sending out confidential information relating to abuse victims.
'Name the villains'
Mr Hill was 12 when he was sent with his two brothers to the Fairbridge Farm School in Western Australia.
He told the hearing: "We'll never be able to undo the great wrong that was done to these children.
"But what is important to the survivors of sexual abuse is where this inquiry is satisfied with the evidence - name the villains.
"Many of them are beyond the grave and therefore beyond the law.
"But it would bring a great deal of the comfort to the people who as children were victims of these people if they were named and shamed."
Inquiry counsel Henrietta Hill QC said claims of "systematic sexual abuse" in institutions and work environments would be heard throughout the inquiry.
The children, she said, were sent without consent of parents, wrongly told they were orphans, and denied basic details about their family backgrounds during their future lives.
For the government, Samantha Leek QC said: "Child migration is wrong. It should not have been sanctioned or facilitated.
"The lifelong consequences for those involved are a matter of deep and sincere regret."
In 2009, the Australian government apologised for the cruelty shown to the child migrants.
Britain also made an apology in 2010. The apology contained no specific mention of sexual abuse.
The first phase of the IICSA inquiry is looking at the way organisations have protected children outside the UK.
Between 7000 and 10,000 children were moved to Australia after World War Two.
They were recruited by religious institutions from both the Anglican and Catholic churches, or charities, including Barnardo's and the Fairbridge Society, with the aim of giving them a better life.
Many, however, went on to suffer physical and sexual abuse in homes and so-called farm schools run by religious orders and charities.
Aswini Weereratne QC, representing the Child Migrants Trust (CMT) support organisation, said this "long overdue inquiry" would hear of a "crushing catalogue of sexual abuse, deprivation, violence and abuse".
Ms Weereratne said the inquiry will hear from 22 former child migrants - their average age was nine when deported and one was aged only three or four years old.
The abuse that some of the children sent abroad were said to have suffered included "torture, rape and slavery", Ms Weereratne said.
A £6m family restoration fund was set up to allow the migrants to travel to the UK and ministers are now considering extending it.
The IICSA has apologised after mistakenly sending out confidential information.
People who had registered an interest in attending victims' forums - which are being organised by the inquiry - were sent an email on Monday that revealed the email addresses of others who had registered.
The BBC understands that 90 people were affected.
Nigel O'Mara, an abuse survivor and core participant in the inquiry, said the data breach was very concerning as they were the very people survivors were supposed to trust with the details of their abuse.
The hearings are taking place at the International Dispute Resolution Centre in central London, with the first phase concerning Australia expected to last 10 days.