By politics.co.uk staff
An investigation has been launched after a teenager placed with a foster family raped and sexually abused their children.
The 18-year-old was taken in by the family who apparently had no idea he had a history of sexual behaviour involving children dating back to 2004.
The teen then raped the couples' two-year-old son and assaulted their nine-year-old daughter.
He has been jailed indefinitely at Cardiff crown court after admitting the charges.
Handing down the sentence, Recorder of Cardiff, Nicolas Crooke, said: "A tragedy ensued for a family who only wished to serve the community and who were let down by the system.
"They were put in a position where they were unable to protect their own children because of a failure to provide them with proper information. My sympathy goes out to them."
Vale of Glamorgan council has launched an internal investigation after admitting a "serious error of judgement" which saw the 18-year-old housed under its adult placement service.
Phil Evans, director of the council's social services, said: "The council has instigated an urgent case management inquiry into the circumstances of the young man's placement.
"The NSPCC has agreed to ensure that this work is done thoroughly. Although the inquiry is still at an early stage, it has become clear that there was a serious error of judgment in placing the young man in this family.
"Staff are taking this matter very seriously. We're doing all that we can to find out what went wrong and to ensure that such events are never repeated."
A spokesman for the children's charity NSPCC added: "The NSPCC can confirm that it has agreed to provide an independent overview of the Vale of Glamorgan Council's internal case management inquiry."
The case comes just months after that of Baby P, whose death at the hands of his mother and her boyfriend, despite several visits from social services, prompted political condemnation of Haringey children's services.