Human rights experts have accused the home secretary, Priti Patel, of ignoring legal guidance in an attempt to target child asylum seekers who cannot prove they are under 18. A letter from the Home Office, seen by the Observer, reveals that the government is putting pressure on social workers to speed up the age assessment of unaccompanied minors, and offering to bankroll councils that face legal challenges as a result. The move comes as new evidence shows that hundreds of people were deported at the height of lockdown, despite the potential health risks. The Home Office letter, which is also signed by officials from the Department for Education, shows that the government intends to intervene in the sensitive task of age assessment by pressuring councils to push children through the process more swiftly. Dated 20 August, it was sent days after Kent county council revealed that it was unable to look after any more unaccompanied child refugees arriving in Dover, because it had reached capacity. The letter reassures councils that the Home Office will help fund any legal challenge arising from children being assessed. It states: “On the question of age, we ask that all authorities with UASCs [unaccompanied asylum-seeking children] they suspect are over 18 are given urgent age assessments. The Home Office can assist with the practicalities of this and offer support in relation to any subsequent legal challenges.” Critics say the reference to appearing “over 18” appears to ignore legal guidance on such cases. Last year a court ruling on the treatment of young asylum seekers stated: “For a person to be assessed as an adult in these circumstances, their physical appearance and demeanour must very strongly suggest that they are 25 years of age or over.” This aggressive approach follows fierce criticism of a video the Home Office released last Wednesday, which labelled lawyers who represent asylum seekers as “activists”. Officials subsequently said the video would be withdrawn. Critics said the latest crackdown risked doing mental and physical harm to child asylum seekers classified as adults in rushed assessments. Dan Sohege, who is director of human rights advocacy group Stand for All and a refugee law specialist, said: “It’s meant to be a very careful, rigorous process and if the Home Office want it pushed through, there are going to be mistakes. They’re just trying to look tough: it seems purely political rather than practical.” Bella Sankey, director of charity Detention Action, said: “This extraordinary letter reveals a Home Office out of its depth and jettisoning all pretence at either competence or humanity. Now it is trying to pressure local authorities to conduct rushed age assessments – with the tawdry offer of funding for the litigation that will inevitably follow.” The UN refugee agency has warned that age disputes have a “devastating impact” on unaccompanied and separated refugee or asylum seeker children. Documenting numerous cases where asylum seekers were initially judged to be adults but later determined to be as young as 15, it said that such teenagers risked being placed in inappropriate adult accommodation and denied access to education Stewart MacLachlan, senior legal and policy officer at Coram Children’s Legal Centre in London, said: “There are already concerns over the age assessment process. If you seek to speed it up, there is a risk that the children have even less chance to understand what they’re going through.” Sankey added: “This is presumably done so that anyone assessed to be over 18 will feel the full force of the lethal hostile environment – destitution, detention and deportation – and the Home Office can curry favour with Nigel Farage’s followers.” The letter urges more local authorities to offer places to accommodate young people from the Kent intake unit in Dover. Kent county council is currently caring for 602 under-18s and 945 care leavers aged 18 to 25. Campaigners have also condemned the deportation of hundreds of people during the lockdown. ONS data shows that in April, May and June – when flights were dramatically reduced – 366 people were forcibly deported. A further 371 agreed to return home, and 1,819 were sent to immigration detention centres. Nadia O’Mara, policy and campaigns officer at Liberty, said: “It is grossly irresponsible to detain and deport hundreds of people during the height of a pandemic. Continuing to enforce the hostile environment during lockdown ensured people without secure immigration status, or those worried for friends and family, could not access health services without fear of detention and deportation.” Last month, Patel promised a review of the hostile environment in light of the Windrush scandal, and a more compassionate, “people first” approach to immigration. A government spokesperson said: “We are exploring with local authorities how we can improve the approach to the assessment of age, so that only those people assessed by experts as being under 18 are being accommodated by local authorities.” They added that every case was evaluated on its individual merits and specialist caseworkers were aware of the importance of making the right decision.