The Home Office is being threatened with legal action over concerns that children face being sent to Rwanda because officials wrongly identify them as adults, the Observer can reveal. With ministers desperate to see flights take off as soon as possible amid a record 181 detected Channel crossings so far this year, the department has been anticipating a flurry of legal complaints to be triggered as a result of the pledge to deport some asylum seekers to the east African country. It has now emerged that it is being challenged over the treatment of those who say they are children but are labelled as adults by immigration officials after an initial assessment of their physical appearance and demeanour. Under the rules of the plan, ministers had promised that no children will be deported to Rwanda once the flights begin this summer. The Home Office is being accused of taking an unlawful approach because it is proposing to deport people based only on an “initial cursory age decision” by an official. An organisation with years of experience on the issue has now issued a pre-action letter – a precursor to legal action – stating that relying on such a thin assessment is “wholly incompatible” with the government’s declared intention of not including children in its Rwanda deportation plan. The department has been given two weeks to respond to the legal threat before further action is taken by the charity. It comes with some organisations warning that they have witnessed deeply troubling mental health issues among children they believe could be in this position. “For years now this government has forced thousands of unaccompanied children into harm’s way, placing them in adult accommodation, camps and adult prisons as a result of its flawed policy of determining age at port of entry,” said Maddie Harris, director of the Humans for Rights Network, the organisation behind the challenge. “Now these children face an extreme and additional threat: forced removal to Rwanda. “We have initiated this legal action to ensure no unaccompanied child is sent to Rwanda, a risk that the children we work with are terrified may become their reality. Since the Rwanda Act was passed we have witnessed an increase in suicidal ideation among our clients and unprecedented levels of fear among these children.” Repeated concerns have been raised about how accurate age assessments have been when dealing with immigration cases. Last year, Dame Rachel de Souza, the children’s commissioner for England, said she had serious concerns about the process and that it must be carried out in “a safe and robust way”. She said that the majority of those who claim to be children and whose age is disputed “are in fact shown to be children on further assessment”. “I am extremely concerned about the way age assessments are currently conducted when children first arrive – they happen very quickly and are not carried out by trained social workers as a full and thorough assessment would be,” she said. “I have met children, living alone in hotels with adults, where a rushed assessment has somehow concluded they are an adult.” Studies have found that large numbers of asylum seekers originally categorised as adults are later proved to be children after more specialist assessments. Data obtained from 70 local authorities last year found that 63% of referrals received from young people who had been sent to adult accommodation or detention were children. The legal letter states that this equates to at least 867 children who had been “exposed to significant risk of potential harm in unsafe adult accommodation or detention as a result of poor initial decision making by immigration officials”. The Refugee Council has also reported that, in 2021, of the 233 young people referred to its services who had been initially assessed as an adult by immigration officers, 94% were later found to be children. Questions about the issue have already been raised in parliament. Labour MP Andrew Western has said there are “numerous cases of children who had been detained as adults being issued with notices of intent to remove them to Rwanda on flights that ultimately never took off”. A Home Office spokesperson said: “We take the safety and welfare of unaccompanied asylum-seeking children extremely seriously, and have been clear that they will not be sent to Rwanda. Many individuals arrive in the UK without documentary evidence and where there is doubt on someone’s age, they undergo an initial age assessment. The lawfulness of our policy on initial age assessments was recently endorsed by the supreme court.” This article was amended on 12 May 2024 to add a statement from a Home Office spokesperson that was received after publication.