The UN has called on the UK and France to halt the controversial “one in one out” asylum system, warning that there may be “serious violations of international human rights law”.

Nine experts, who include seven special rapporteurs, wrote a 20-page letter to Downing Street and Paris on 8 December 2025 outlining detailed concerns about potential breaches of human rights they have identified in the scheme. They gave the two governments 60 days to respond and on Friday published their letter.

It contains detailed case studies documenting the treatment of people placed in detention in preparation for being forcibly removed to France under the scheme. They include asylum seekers from Sudan, Gaza, Eritrea, Yemen and Iran, many of whom are survivors of torture and trafficking.

The experts said the detention of torture survivors for the scheme “may in itself amount to cruel, inhuman and degrading treatment”.

The concerns expressed by the UN experts echo those raised by asylum seekers themselves. The Guardian previously revealed that one man who was returned to France came back to the UK due to fear of smugglers, while those detained issued a series of reports about their treatment in detention and staged a peaceful protest against the scheme while detained, which was responded to by Home Office contractors with riot shields, tear gas and dogs.

According to the letter, a man from Eritrea was not allowed to wear shoes for his removal, had a hood placed over his head and was forced to the ground with boots of guards placed on his neck. A woman from Yemen, who said she had been enslaved since the age of three, was told by the Home Office that her account was not credible because she had not immediately disclosed her trafficking history on arrival in the UK.

The letter states: “We are deeply concerned that the agreement between the [UK and France] … may result in serious violations of international human rights law,” saying they had received information concerning human rights violations of “children and those in vulnerable situations”.

The letter poses a series of questions to the two governments relating to unpublished information about the scheme, such as the apparently arbitrary nature of who among small boat arrivals is selected for detention and forced return to France and who is allowed to have their asylum claims processed in the UK. They also ask about protection from onward refoulement once people are sent back to France.

It says: “We therefore respectfully call [the UK] government to end this agreement with France and ensure that migration governance measures respect, protect and fulfil human rights and not create new situations of vulnerability or exacerbate existing ones.”

Bella Mosselmans, director of the Global Strategic Litigation Council for refugee rights, backed the UN experts’ call for the scheme to be scrapped. She said: “People directly affected by these policies have stood up for themselves, speaking out about the fear, detention and harm they have endured.

“The UN has now echoed those lived experiences with a clear and urgent alarm. These UN experts have documented detailed, credible cases showing that this agreement exposes people to serious human rights violations – including threats to life, torture and other ill-treatment, and the denial of due process. Continuing to implement it despite those warnings is indefensible.”

“We are already aware of dozens of children caught up in this scheme, despite being explicitly excluded from it, many of whom are survivors of trafficking. This letter from nine human rights experts sounds a clear alarm. The UK and France must listen, act now, and stop the harm they are causing.”

The Home Office, French interior ministry and the UN Refugee Agency have been approached for comment.