More than 830 UK health professionals and representatives from leading medical bodies have signed a letter to the prime minister expressing “grave concerns” that the government’s plan to send asylum seekers to Rwanda will cause “catastrophic mental and physical harm” to people seeking safety, in advance of a court of appeal hearing on the policy on Monday. Signatories to the letter include the BMA and the Royal College of Obstetrics and Gynaecologists. “Subjecting people seeking sanctuary in the UK, many of whom have mental health conditions and have histories of torture, trafficking and trauma, to such an inhumane process is a matter of significant concern for the medical community,” the letter says. Like Brexit, the government’s plans to send asylum seekers to Rwanda has split the UK down the middle. According to a poll carried out by the More In Common thinktank carried out this month, almost half of those surveyed (46%) back the deal, announced just over a year ago. It has so far cost £140m, although no asylum seekers have yet been sent to the east African country. On Monday the plans will be considered in the court of appeal by three top judges – the lord chief justice, the master of the rolls and Lord Justice Underhill, vice-president of the court of appeal’s civil division. A group of asylum seekers from countries including Iran, Iraq and Syria are bringing the appeal, along with the charity Asylum Aid. In the high court last December, two senior judges found that the government’s plans were lawful but quashed the cases of eight individual asylum seekers threatened with removal to Rwanda. While the ruling was welcomed by the government and the former home secretary Priti Patel, who announced the Rwanda deal on 14 April 2022, permission to appeal was granted on some grounds. Last month, further permission to appeal was granted to consider whether the high court judges had properly examined if Rwanda is a safe place to send asylum seekers. Grave warnings were given by the UN refugee agency the UNHCR, which was given permission to intervene in the high court case and give additional information concerning Rwanda’s poor track record of protecting refugees. The government insists that the plan to send asylum seekers to Rwanda is workable and an essential deterrent to prevent large numbers of people crossing the Channel. The prime minister, Rishi Sunak, has made “Stop the boats” one of his key undertakings before the next election. Last year a record 45,756 people crossed the Channel in small boats. So far this year more than 5,000 have made the crossing, a similar figure to this time last year before the Rwanda announcement was made. A decision known as an “interim measure” was issued by the European court of human rights hours before the first Rwanda flight was due to take off on 14 June last year, which halted the flight. The ECHR said it took particular account of evidence that asylum seekers transferred from the UK to Rwanda will not have access to fair and efficient procedures for the determination of their asylum claims. The interim measure expired after the quashing of the individual asylum seeker’s threatened removal to Rwanda by the two high court judges. But earlier this month the ECHR announced that it had accepted a new application. The asylum seeker from Iraq, known only as NSK, is claiming that it would be a breach of his human rights to send him to Rwanda as he would be at risk of “inhuman and degrading treatment” and could not expect a fair assessment of his application. The ECHR said it had “given notice” to the UK government about NSK’s case and requested that ministers submit their observations. The Rwanda plans have been criticised by many human rights organisations. The UN’s special rapporteur on trafficking in persons has been granted permission to intervene in this week’s court of appeal hearing along with the UNHCR. The government has pledged to start sending asylum seekers to Rwanda as soon as legal proceedings have concluded. A Home Office spokesperson said: “Our migration and economic development partnership will see people who come to the UK through dangerous and illegal routes relocated to Rwanda, where they will be given the opportunity to settle and rebuild their lives. “Individuals who are eligible for relocation will have all their needs looked after while their asylum claims are being considered in Rwanda including having access to safe and clean accommodation and healthcare.”