Migrant children could be mistakenly sent to Rwanda if the Home Office wrongly decides they are adults, campaigners have warned.
The Refugee Council raised the concerns after highlighting errors it claims were made in some of the department’s age assessments for youngsters who have sought asylum in the UK.
The charity said it has “already had to intervene to stop children who were incorrectly assessed as adults from being detained awaiting removal to Rwanda”.
It called on the Government to make sure no child deemed to be an adult by the Home Office is “threatened” with deportation to the east African nation until a “professional assessment” by a social worker had taken place.
The Home Office previously insisted lone migrant children would be exempt from being sent to Rwanda, although families could be in line for removal.
It comes as Channel crossings resumed after a five-day hiatus.
A report published by the charity on Friday said 94% of 233 children it supported last year were wrongly considered to be aged over 18 by the Home Office. Only 14 were found to be adults.
In more than half of the cases the Government department claimed the children were at least 25 if not older, according to the findings.
Enver Solomon, the charity’s chief executive, said the blunders were down to “hasty and woeful” decision-making and that such mistakes leave children at risk of abuse and neglect, as well as without proper support or education.
He said: “Every day refugee children are at risk of abuse and neglect because hasty, woeful decision-making routinely mistakes them for adults. Time and again the Government claims that people are always lying about their age but the evidence shows they are not.
“We are very worried that children are going to be sent to Rwanda, which will have devastating consequences for young people who have already suffered so much.
“We urge the Government to immediately take heed of our recommendations and do better by vulnerable children it has a duty to protect.”
In January the then home secretary Priti Patel called in scientific advisers in a bid to use X-rays and other medical checks on asylum seekers to stop grown men “masquerading as children” on their applications.
The number of adult asylum seekers falsely claiming to be children is a “significant issue”, the Home Office said as it announced it was setting up a scientific advisory committee to get advice on ways of checking the ages of those arriving in the UK.
The committee is considering the accuracy and reliability of a “range of scientific methods for estimating age”, as well as ethical and medical issues, before reporting its findings.
But the Council’s report described the plans as “flawed”, adding that they risk more children being wrongly treated as adults with some “forced to go through scientific procedures that are not reliable.”
The Government needs to be more transparent by publishing “adequate and accurate” data on the subject so the true scale of the problem can be known, the charity also said.
Data highlighted by fellow charity the Helen Bamber Foundation suggested there could be a more widespread problem, with figures obtained under freedom of information laws indicating there were 450 young people referred to council children’s services after they were initially sent to adult accommodation and detention. Three quarters were found to be under 18.
More than 32,300 people have crossed the Channel to the UK so far this year, government figures show.
This includes more than 7,200 in September so far.
Children wrapped in blankets were among the latest arrivals pictured being brought ashore in Dover, Kent, on Thursday.
Since Ms Patel announced her plan to send migrants to Rwanda in April, more than 27,000 people have made the crossing.
Prime Minister Liz Truss said the Government would press ahead with the plan, which has so far been disrupted by a series of legal challenges.
A Home Office spokesperson said: “Age assessments are challenging but vital. Children are at risk when asylum seeking adults claim to be children, or children are wrongly treated as adults.
“Our reforms through the Nationality and Borders Act aim to make assessments more consistent and robust by using scientific measures, and creating a new National Age Assessment Board. If there is doubt whether a claimant is an adult or child, they will be referred for a local authority assessment and will be treated as a child until a decision on their age is made.”