They are Cambodia's stolen generation.
More than 35,000 children and young people are living in the country's orphanages and other institutions, including some run and financed by Australians, according to a new study.
Cambodia's Ministry of Social Affairs has vowed to crack down on 639 residential care institutions, many of which have been dogged by claims of child sexual abuse and the exploitation of children as tourist attractions.
The ministry's study, which was supported by the UN children's agency UNICEF, found that 38 per cent of the institutions have never been inspected, 12 per cent are unregistered and more than 20 per cent did not have a memorandum of understanding with the government.
"The finding that many residential care institutions are out of the ministry's regulatory framework raises significant concerns for the wellbeing of children living in them," said Voung Sauth, the Minister for Social Affairs, Veterans and Youth Rehabilitation.
"Decades of global scientific research has shown that living in residential care can harm a child's social, physical, intellectual and emotional development with long-term impact on adult life," he said.
Research shows that most of the children in Cambodia's orphanages are not orphans and have at least one parent.
Mr Sauth urged poverty-stricken parents not to allow their children to be placed in orphanages, saying the best place for them was in the care of their families.
But the study said reasons for children to be sent to the institutions, other than poverty, included divorce, illness or a large number of children in the family, migration and a lack of social welfare services.
The study found that institutionalising children should only be a last resort and then only be temporary, including for those who are disabled or suffering from HIV/Aids.
Cambodia's government has been under growing pressure from UN agencies and non-government-organisations for several years to close the country's orphanages, many of which are run by religious organisations.
Fifty-seven orphanages were shut last year.
But until now the government has allocated scant resources to police regulations.
Following the study, Mr Sauth said his ministry was committed to reintegrating 30 per cent of the children living in residential care centres to their own communities by 2018.
Children under three will be banned from any centre.
The number of orphanages in Cambodia has doubled in the past five years while they are banned in most Western nations.
The study found there are "stark gaps in Cambodia's care system, confirming long-held concerns of the government and child protection workers for the wellbeing of children living in unmonitored institutions and of the uncontrolled increase in orphanages in the country".
Welfare workers have condemned the recruitment of volunteers from universities in Australia and other countries to work in orphanages.
They say so-called "orphan tourism" and "volunteer tourism" in thinly disguised orphanage businesses exploit the children, tourists and volunteers.
"Your donations don't help orphans - they create them," says a blunt message from the Phnom Penh-based NGO Friends International.
