The number of children in care in England and Wales who have restrictions placed on their freedom has tripled in the last two years, BBC News has found.
Deprivation of liberty orders are increasingly being used to detain children in homes when suitable accommodation cannot be found.
Campaigners say it shows a "wilful neglect" of young people at risk of exploitation.
The government said supporting vulnerable children "is a priority".
Deprivation of liberty orders are often used for adults who lack the mental capacity to consent to changes in their care, such as elderly people with Alzheimer's.
But BBC News has learned they are increasingly being used for children and young people on safeguarding grounds.
The orders can cover a range of restrictions from detention in a house to taking away a mobile phone - and are commonly secured from the High Court or Court of Protection by a local authority in charge of the care of the child.
- Do you know someone placed on a Deprivation of Liberty order? Email email@example.com
Freedom of information responses from 91 of 170 local authorities in England and Wales show the number of deprivation of liberty orders for children and young people went from 43 in 2016-17 to 134 in 2018-19. The vast majority of these will be for children in care.
More than a quarter of orders granted over the last five years were made primarily because of concerns about the child or young person going missing, without relating to mental capacity.
One recent hearing granted a deprivation of liberty order for a 13-year-old child to be detained in a rented council house while being cared for by four local authority staff.
The order meant the child could be locked in a bedroom at night, stripped of all loose items and restrained if attempting to self-harm, hurt staff or escape.
The judgement acknowledged the restrictions were "draconian" but said 30 applications for a place in a secure unit or alternative settings had been declined.
At another hearing, a High Court judge complained of being "almost drowned out" by applications at that time and said he was increasingly concerned they were "operating to bypass" safeguards provided by secure accommodation.
BBC News has learned a 14-year-old victim of so-called modern day slavery had been placed on a deprivation of liberty order and was moved to an unregulated home.
Despite being banned from having a mobile phone because of her vulnerability, the girl told a social worker she was given an iPhone and moved between residences across the UK by a company, sometimes without the local authority being informed.
The number of children waiting for placements in secure accommodation - residences children are prevented from leaving - hit a peak of 54 open referrals in England, according to records released by the Department for Education following a freedom of information request.
BBC News has learned three children have spent more than six months waiting for a secure accommodation placement, and one child had 27 individual referrals declined.
The lack of appropriate placements for such children and young people is an "absolute disgrace", according to Carolyne Willow, director of the charity Article 39, which campaigns for the rights of children in institutional settings.
"It demonstrates wilful neglect at the highest level and a readiness to permit the decaying of children's services.
"You don't have to be a child welfare expert to be able to imagine the risks of putting an individual child into accommodation where there's no other children… where everything you do is monitored and supervised, where every aspect of ordinary childhood experiences are taken from you."
Such orders "are meant to be last resort measures, they're not meant to be regular, routine ways of protecting children", she said.
Investment is needed, not only in secure accommodation, but a range of specialised placements that cater to the dangers now faced by vulnerable children, said Jenny Coles, the President of the Association of Directors of Children's Services.
"The children, young people, that are coming into care over the last three or four years, their needs and their experiences have changed", she said. "[These range] from sexual exploitation, criminal exploitation, gangs, county lines.
"If we had that broader range [of placements], that was meeting complexity, we wouldn't have to potentially use those orders as we have been using them."
In a statement, a government spokesperson said: "Supporting the most vulnerable children in the country is a priority for this government, and every young person in care deserves appropriate, safe accommodation that supports them in the best way possible.
"Local authorities have a duty to make sure there are sufficient places, including secure care, for their looked-after children.
"We have invested £40m in supporting councils in England to improve and expand the secure provision available, and we have consulted on radical reforms to the quality of independent and semi-independent placements to make sure the right checks and balances are in place."
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