Australia opened a national probe into child sex abuse on Wednesday, with premier Julia Gillard warning of "uncomfortable truths" as institutions including schools and churches come under scrutiny.
Gillard ordered the inquiry in November after a decade of growing pressure to investigate widespread allegations of paedophilia, two months after the Catholic Church in Victoria revealed hundreds of children had been abused.
"This is an important moral moment for our nation," Gillard told ABC radio as the Royal Commission into Institutional Responses to Child Sexual Abuse began at the Victorian County Court in Melbourne.
"When I established this royal commission I understood that it was going to require our whole country to stare some very uncomfortable truths in the face," the prime minister said.
Chairman Justice Peter McClellan announced at the opening that the inquiry would hear "serious and shocking allegations".
At least 5,000 people would want to tell their stories, although "the number could be much higher", he said. Public hearings are not likely to start for several months.
"Part of the task given to us... is to bear witness, on behalf of the nation, to the abuse and consequential trauma inflicted on many people who have suffered sexual abuse as children," he said.
"For the individuals who have been traumatised, giving an account of their experiences and telling their story can be an important part of the recovery process."
An interim report is due by June 2014 but McClellan admitted it was unlikely the commission could complete its work within the timeframe for the delivery of a final report in June 2015. Findings and recommendations will be made public.
Gillard outlined two goals for the inquiry.
"For the survivors of child sexual abuse, I want this to be a moment of healing, for us to say to them as a nation 'we hear you, you're valued and you're believed' because for too long, so many of these survivors have just run into closed doors and closed minds."
"And second, I want the royal commission to provide for us recommendations about the future.
"We've let children down in the past as a country. We need to learn what we can do as a nation to better protect our children in the future."
Counsel Gail Furness told the inquiry that orphanages, schools, churches, parishes, groups such as the scouts, organised sports, childcare centres, detention centres and the defence forces would all come under scrutiny.
But she added: "The royal commission is not a court and does not decide criminal cases."
The inquiry would be conducted to understand the response of an institution to an allegation of abuse.
Australia's most senior Catholic cleric apologised at Christmas to those who "suffered at the hands" of priests and religious teachers.
Sydney Archbishop George Pell said he was ashamed following a series of paedophile allegations against priests and claims they were hushed up.
The government in Victoria state is running its own investigation into sex abuse, with the Church telling a state parliamentary hearing in September that about 620 children had been abused since the 1930s.
There is also a special commission of inquiry in neighbouring New South Wales into similar allegations raised in the Hunter Valley, north of Sydney.
Child sex abuse allegations have rattled the Catholic Church across the world, particularly in Ireland but also in the United States, Germany and Belgium.