Hundreds of asylum seekers, including at least 41 children whose ages are in dispute, have gone missing after being forcibly returned to France under a controversial "one in, one out" agreement between the UK and France. Human rights organizations have raised alarms about the situation, citing reports that these individuals are now living in hiding across Europe. The agreement, announced in July 2025 by former UK Prime Minister Keir Starmer and French President Emmanuel Macron, was initially described as a "groundbreaking" approach to managing migration. Under the deal, one asylum seeker arriving in the UK by small boat is returned to France in exchange for another asylum seeker who enters the UK legally from France. However, the scheme is set to expire on 1 October, and it remains unclear what, if anything, will replace it. The UK’s Home Secretary, Shabana Mahmood, has reportedly pushed for the agreement to be extended and expanded, but the French government has expressed a preference for a broader European approach to managing asylum seekers rather than placing the burden solely on France. A French politician told The Guardian that attempts to persuade other countries to take back a share of small-boat arrivals have met with resistance. Since the deal began in September 2025, about 1,400 asylum seekers have been returned to France, but this represents only 4% of the 32,000 who have crossed the English Channel by small boat since the agreement was signed. These numbers do not include those who have returned to the UK a second time, some of whom are now living in hiding. At a parliamentary meeting chaired by Lord German, a general rapporteur on asylum and migration policy, and Alex Sobel, the new chair of the joint committee on human rights, representatives from human rights organizations highlighted concerns about the scheme. They reported that at least 41 children and young people whose ages are in dispute have been unlawfully returned to France. The UK Home Office has denied these claims, stating that no one whose age is in question has been returned to France and that all detained individuals are advised of their legal rights within 24 hours of arrival at an immigration removal center. However, independent monitoring boards for prisons and detention centers reported that nearly 100 children had been unlawfully detained as part of the scheme, as the Home Office is reportedly detaining more people than it can process for removal. French officials told The Guardian that only 200 of the people forcibly returned to France are still in contact with local authorities, while hundreds of others have gone underground across Europe. Returnees interviewed by the newspaper described being forced into hiding due to fear of being sent back to their home countries, where they believe they would be unsafe, or due to threats of deportation to other European countries like Bulgaria. Meanwhile, Médecins Sans Frontières reported that many asylum seekers returned to France are in severe psychological distress, with symptoms including flashbacks, anxiety, self-harm, and suicidal thoughts. Alex Sobel expressed deep concern over the increasing militarization of the French border to prevent asylum seekers from crossing into the UK, saying that some actions by French police would be unacceptable if carried out by British authorities.