Calls are mounting for the Home Office to shut down a controversial barracks in Kent used to accommodate hundreds of asylum seekers after a damning high court ruling. Six asylum seekers won a legal challenge against the government on Thursday after a judge ruled that their accommodation in the barracks failed to meet a minimum standard. The court found that Napier barracks in Folkestone, Kent, provided inadequate accommodation for asylum seekers and that the home secretary’s process for selecting people to be accommodated at the site was flawed and unlawful. It also found that residents of the barracks were unlawfully detained under purported Covid rules. Lawyers and human rights organisations including the Red Cross, Liberty, the Helen Bamber Foundation and the Joint Council for Welfare of Immigrants said alternative accommodation that was safe and decent should be provided. The Home Office has an agreement to use the barracks until September, but campaigners fear it might extend its use of the barracks despite the mounting criticism from many quarters including the courts, independent inspectors and charities about their unsuitability. Home Office sources said that any use beyond September would require discussions with the Ministry of Defence and the local planning authority. A letter seen by the Guardian from the immigration minister Kevin Foster to the all-party parliamentary group on immigration detention dated 2 June states that the Home Office has carried out a “lessons learned” exercise and has input from various health officials including at the Joint Biosecurity Centre to manage any future Covid infections. Thursday’s high court ruling relates to a case brought by six asylum seekers who were housed in Napier barracks between September and February. All were vulnerable victims of trafficking and/or torture who had experienced a deterioration in their mental health as a result of their accommodation and were transferred elsewhere after legal proceedings were initiated. The court heard evidence that the home secretary decided to use dormitory accommodation at the barracks despite advice from Public Health England (PHE) that it was not safe to do so during the Covid pandemic. The precautions that were taken were inadequate to prevent the spread of Covid-19, which resulted in a widespread outbreak affecting half of the almost 400 residents there. On Thursday Mr Justice Linden ruled in favour of the men and found that the Home Office had acted unlawfully when deciding the former military camp was appropriate. He referenced overcrowding and the failure to follow PHE advice among the reasons the barracks were unlawfully unsuitable. “Whether on the basis of the issues of Covid or fire safety taken in isolation, or looking at the cumulative effect of the decision-making about and the conditions in the barracks, I do not accept that the accommodation there ensured a standard of living which was adequate for the health of the claimants,” he said. “Insofar as the defendant considered that the accommodation was adequate for their needs, that view was irrational.” He found that from 15 January, when an instruction was given that residents were not to leave Napier barracks without permission, the claimants had been unlawfully detained. After emptying the barracks on 9 April the home secretary began refilling the accommodation. There are more than 265 residents sleeping in dormitories of up to 12 people. Since 9 April more than 45 people have been transferred out of the barracks on the grounds of vulnerability following the threat or issuing of legal proceedings. Satbir Singh, the chief executive of the Joint Council for the Welfare of Immigrants, said: “Today’s judgment proves that this government not only ignores its own rules but that it is reckless with people’s lives. Asylum seekers were unlawfully detained in appalling, crowded conditions. There is no place for sites like these in our communities and they must be shut down immediately.” A Home Office spokesperson said: “During the height of the pandemic, to ensure asylum seekers were not left destitute, additional accommodation was required at extremely short notice. Such accommodation provided asylum seekers a safe and secure place to stay. “Throughout this period our accommodation providers and subcontractors have made improvements to the site and continue to do so. It is disappointing that this judgment was reached on the basis of the site prior to the significant improvement works which have taken place in difficult circumstances. Napier will continue to operate and provide safe and secure accommodation. We will carefully consider the ruling and our next steps.”