Most of the asylum seekers initially earmarked for deportation to Rwanda cannot be immediately located, the Home Office has admitted.
Documents show 5,700 asylum seekers have been identified in the initial cohort to be sent to Rwanda.
But only “2,143 continue to report to the Home Office and can be located for detention”, the documents say.
No 10 said it was “not accurate” to say the Home Office was unable to locate the others.
The PM’s spokesman said: “The Home Office continues to have a wide range of tools to maintain contact with them, those include face to face and digital reporting, and of course many individuals are residing in Home Office accommodation.
“The Home Office remain confident of their whereabouts.”
Many asylum seekers do not stay in Home Office accommodation, and there are different ways they must report to the Home Office.
Some have to do so in person while others can report digitally and face less strict requirements.
A government source admitted it was possible some could abscond before they were detained.
An ex-border force chief said asylum seekers had performed a “disappearing act” now they faced deportation.
Kevin Saunders, former chief immigration officer at Border Force from 2001 to 2016, said he was not surprised “in the slightest” the Home Office had lost contact with asylum seekers.
Mr Saunders Radio 4’s Today programme asylum seekers had “ignored” the Rwanda plan until now as they were told it would never happen.
He accused the Home Office of “telling porkies” by claiming the asylum seekers are not missing.
But the fact asylum seekers were “disappearing already” shows the Rwanda scheme is working as a deterrent, he added.
Under the law, migrants without permission to stay in the UK should only be detained if their flight is reasonably imminent.
That means that almost all those who have crossed the English Channel are in Home Office-provided accommodation.
They are given a phone to maintain contact with officials and instructions to report to one of 13 immigration offices, or their nearest police station – but the rules are flexible.
The Home Office’s immigration reporting rulebook says that asylum seekers who have “no realistic timescales” for a final decision may only need to report in person every three months. The group of people who could be sent to Rwanda should “generally” report every two weeks – but that rule does not appear to be fixed.
Last December the Home Office separately stopped a pilot scheme to GPS-track 600 asylum seekers, by placing tags on their ankles.
The UK’s data protection watchdog said that 18-month long pilot scheme had been unlawful.
Health Secretary Victoria Atkins said the “Home Office is used to” being unable to contact some asylum seekers.
She told Sky News: “Law enforcement have a variety of measures to find people, they will be found and they will be removed.
“We want the message to go out loud and clear that if somebody doesn’t report as they should do, they shouldn’t think that they’ll get away with it.”
Labour’s shadow immigration minister Stephen Kinnock said: “This latest farce exposes the total lack of grip the Conservatives have over the asylum system and the chaos at the heart of their Rwanda policy.
“The prime minister promised to detain and remove all those who crossed the Channel. Now he can’t even locate those intended for removal.
“How can the Conservative Home Office keep losing so many people?”
Reuters Prime Minister Rishi Sunak during a press conference in the Downing Street Briefing.
Prime Minister Rishi Sunak has promised the first deportation flights to Rwanda will take off by July
The policy document sets out details of the 5,700 people that Rwanda has “in principle” already agreed to accept. Those identified in the initial cohort all arrived in the UK illegally between January 2022 and June 2023.
They had already received a “notice of intent” that their asylum claims were inadmissible and they were being considered for deportation to Rwanda before the Court of Appeal ruled the policy was unlawful on 29 June 2023.
It means no-one who arrived on a small boat since last summer will be removed in the first flights to Rwanda.
The updates, contained in an “equality impact assessment”, also raised the possibility that lobbying from MPs could delay an asylum seeker’s removal.
“It is a long-standing parliamentary convention that MPs’ representations suspend removal until a case has been considered and a response issued to the MP,” the document said.
It added that given the “novel nature” of the Rwanda scheme, individual cases could “attract significant attention from MPs, and responders may be overwhelmed by cases, causing a delay or removal to be cancelled pending a response”.
A Home Office spokesperson said caseworkers had been put in place to respond to MPs quickly.
Prime Minister Rishi Sunak has promised these will take off by July, after legislation enabling removals entered into force last week.
The scheme is a key part of his flagship pledge to stop small boats crossing the Channel.
A Home Office spokesperson added: “In preparation for flights taking off, we have identified the initial cohort to be removed to Rwanda and have hundreds of dedicated caseworkers ready to process any appeals.
“It would be inappropriate to comment further on operational activity.”
The government has never put a figure on the total number of asylum seekers who could be sent, insisting the scheme is uncapped.