Undocumented migrants living in the UK and their children face hostility from officials and the public, ill-health, self-harm, and even suicide, according to a consultation, whose report is published today.
Evidence given to University of Manchester academics and the Migrant Rights Network by the 'sans papiers', also echoes critical press reports on Yarl's Wood Detention Centre, Bedfordshire.
The team, who are calling for a public enquiry, were told by migrants that the centre's medical services and living conditions are not up to standard, also citing other problems around privacy and hostile staff.
Dr Jon Spencer, based at the University's School of Law, who lead the study, said: "This research reveals how many undocumented workers are trapped in a Kafkaesque world, where rules change without notice and the demands are unreasonable.
"Access to services seems to be arbitrary and discretionary and officials can make decisions without any justification or reasonable explanation.
"Though the number of undocumented migrants in the UK probably fell in recent years, we are concerned about the welfare of those that remain."
He added: "This is why we are calling for a public inquiry to ensure the UK's detention estate conform to minimum standards elsewhere in the criminal justice system.
"Indeed, the whole of the asylum system must conform to criminal justice standards.
"In particular, we think there should be a maximum time limit for immigration detention, proper access to medical care, and an end to the use of force during detention and removals."
The undocumented migrants interviewed by the team were mostly asylum seekers overstaying their visa and workers who entered the country on false papers, in search of clandestine, low paid, employment.
Ruth Grove-White from the Migrants Rights Network said: "This study shows how urgently a rethink is needed to tackle the way we respond to irregular migration. There are many reasons why people become undocumented, and its often related to problems in the immigration system itself.
"But the approach of the current government is to come down hard on undocumented migrants. Soon, local hospitals, landlords and employers will all be on the frontline, expected to identify and report those without papers. But outsourcing immigration controls in this way is tearing communities apart.
"We'd like to see government taking real steps to address the causes of irregularity, and to ensure that everyone in the UK, regardless of their status, is treated with dignity and compassion."
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