More than 2,000 children who have been trafficked or who arrived in the UK alone to claim asylum disappeared from social services’ care last year, according to freedom of information data shared with the Guardian.

The authors of a report, Until Harm Ends, submitted FoI requests to children’s services departments in councils across England, Wales, Scotland and Northern Ireland asking for information about trafficked children and those who arrived alone in the UK and claimed asylum, who then went missing after being taken into care.

Data from 135 local authorities revealed that out of 2,335 children identified as having been trafficked or suspected of having been trafficked, 864 (37%) were reported missing.

A total of 141 local authorities responded to questions about lone child asylum seekers in their care, who amounted to 11,999 children. Of these, 1,501 (13%) were reported missing.

The report, published on Monday by the charities ECPAT UK (Every Child Protected Against Trafficking) and Missing People, warns that these groups are at “very high risk” of going missing from care.

A vigil for refugee children missing from UK care in Falmouth, Cornwall, in January 2023. Photograph: Jory Mundy/Alamy

Some trafficked children in the UK are British citizens while others are from overseas. They are likely to have been subjected to either sexual exploitation or criminal exploitation, for example by county lines gangs.

Local authorities have a statutory duty to safeguard and support trafficked and unaccompanied children under child protection frameworks. However, there is no published central government data on the issue.

The new report warns that factors such as insecure immigration status can heighten young people’s vulnerability to further harm, placing them at significant risk of re-trafficking and renewed exploitation.

It says there is a “continuing and significant failure” in safeguarding and calls on local authorities and police to ensure adherence to good practice.

The authors also urge the Department for Education to ensure all trafficked and unaccompanied children can access appropriate accommodation that protects them from being exploited again.

Since September 2021, local authorities have been required to ensure that all looked-after children under 16 are placed in settings that provide care. However, 16- and 17-year-olds can still be housed in so-called “supported accommodation” that does not provide day-to-day care.

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In exceptional circumstances, these older children can be placed in hostels, caravans, tents, boats, or shared housing with unrelated adults.

Patricia Durr, the chief executive of ECPAT UK, said: “This report highlights the risk trafficked and unaccompanied children face. It remains challenging to understand why these children continue to be failed. They are consistently let down by the systems meant to support them, whilst being punished by policies that exacerbate the problem and used by a political rhetoric that seeks to create division.”

Jane Hunter, the head of research and impact at Missing People, said: “Every child deserves to feel safe and protected, yet trafficked and unaccompanied children are repeatedly failed by the very systems designed to safeguard them.”

A government spokesperson said: “This government inherited a children’s social care system failing to meet the needs of the country’s most vulnerable children. Our landmark children’s wellbeing and schools bill is the biggest overhaul of children’s social care in a generation, delivering on our mission to break the link between young people’s background and their future success, and to ensure every child in our country, including those in care, has the opportunity to thrive.

“This includes improving the availability of care placements, better information sharing, requiring the establishment of multi-agency child protection teams in every area, and introducing a new duty on partners to automatically include education and childcare settings in their safeguarding arrangements to help prevent children falling through the cracks.”