Missing children in care: AM Joyce Watson's abuse fears
Children in care are at risk of sexual and physical abuse as some Welsh councils fail to report and record when they go missing, it is claimed.
Joyce Watson, chair of the Welsh assembly's human trafficking group, fears some may be preyed on by gangs of abusers.
Children targeted by gangs for sexual exploitation are often in care.
Ms Watson spoke ahead of a Gwent Police drive to bring together councils and other bodies when children go missing.
The new initiative - called Missing Children's Hub - will be launched on Monday in a bid to intervene early when young people disappear.
Ms Watson told the Sunday Politics Wales on BBC One Wales that children in care are at risk of abuse and exploitation.
"These are vulnerable children," she said. "One of the clear bits of evidence that has come out is that vulnerable children that go missing are even more vulnerable and likely to fall victim to abuse or sexual exploitation."
The programme said that Wales' 22 local authorities showed inconsistencies in how they recorded and reported cases of children who go missing.
More than a quarter of councils reported having no central record of missing children. A further five councils had figures only for children missing for more than 24 hours.
The Welsh government issued guidance in 2011 which states that the disappearance of young people from care should be reported if they are absent for more than six hours or after midnight.
Sion Gwilym, a family law solicitor specialising in "looked after" children - those in care or foster homes - said councils had a responsibility as the "corporate parents" of these young people.
"A looked after child or a child who's in the care of his or her family - there should be no difference," he said.
"There should be the equal level of concern and there should be the same reaction involving the police and making inquiries to find that child."
The Welsh Local Government Association (WLGA) said it worked with the Welsh government and social services to develop "robust child protection policies".
"Alongside our delivery of the all-Wales child protection procedures and trafficking protocols, we continue to actively work with partners such as the Care and Social Services Inspectorate to continually improve our services," it added.
Jeff Farrar, deputy chief constable of Gwent Police, said people who go missing repeatedly were "invariably looked after children" who needed "multi-agency support".
"This is not just an issue for the police," he said. "This is about the local authorities, it's about health, it's about the third sector, coming together and recognising that when somebody goes missing in those circumstances, they are incredibly vulnerable."
Mr Farrar is the lead figure on human trafficking with the senior police officers' organisation Acpo Cymru, and he believes the Gwent scheme will eventually be rolled out across Wales.
The Welsh government endorses this new approach, and a spokesperson said safeguarding children was a "key priority".
"We have published guidance to help protect children from sexual exploitation by helping practitioners identify children at risk, take steps to protect them and allow action to be taken against perpetrators."
The Sunday Politics Wales is on BBC One Wales from 11:00 GMT on Sunday.