The Home Office has admitted that the number of missing migrants is even higher than they previously thought.
In a letter to MPs, ministers admitted to having lost track of 5,600 asylum claimants whose applications have been discontinued.
The letter, from migration ministers Tom Pursglove and Michael Tomlinson to Dame Diana Johnson, Chair of the Home Affairs Select Committee, saw the Home Office admit it is trying to "urgently reestablish contact" with the missing asylum seekers.
The figures were published after officials said they did not know where 17,000 former claimants were.
The Home Office has admitted that the number of missing migrants is even higher than they previously thought
PA
The Commons Home Affairs Committee demanded answers on the whereabouts of the individuals.
Earlier this week, official documents revealed that only 4,200 people earmarked for deportation were in "regular contact" with Home Office.
But the latest admission from the Home Office shows that the figure is closer to 6,000.
Shadow Home Secretary Yvette Cooper said the admission is "yet more evidence" of "shocking mismanagement and chaos in the Tory asylum system".
She said: "This is a staggering admission that the Home Office has lost almost 6,000 asylum seekers and has no idea where they are.
"The fact that thousands of people have been allowed to effectively disappear into the underground economy or left vulnerable to exploitation by criminal gangs is yet more evidence of the shocking mismanagement and chaos in the Tory asylum system.
"Time and again ministers are spending their time on gimmicks rather than getting a grip."
The letter from Pursglove and Tomlinson said: "It is erroneous to say that the Home Office has lost the 17,316 cases that have been withdrawn over the 12 months to 30 September 2023. There are a variety of reasons for an asylum claim to be withdrawn, including voluntarily by individual claimants or by the Home Office, for example as a result of not attending interviews or failing to meet reporting requirements."
They admitted that "5,598 remain in the UK and the Home Office is taking steps to urgently reestablish contact with them".
The ministers added: "When we withdraw a claim, and if someone has no other permission to stay in the UK; funding and support stops and someone becomes liable for law enforcement activity to be removed from the UK. If these individuals were to make further submissions, caseworkers may consider whether their previous actions are damaging to their credibility."
Today it was revealed that the Home Office has hired an aircraft hangar and aeroplane fuselage so that security officials can practice forcibly removing migrants onto planes in preparation for Rwanda deportation flights.
As part of their training, staff will practice different scenarios that they are expected to encounter when they transport migrants onto planes bound for Rwanda.
Sources told the Times that security guards have undergone special training programmes to help them deal with "disruptive" passengers.
They are expected to practice scenarios ranging from violent individuals to Extinction Rebellion style protests where individuals "play dead" - lying on the floor and refusing the move.
The Home Office estimates that five officers will be needed for each migrant removal.
A spokesperson for the Home Office told the Times that the plans were vital to ensure that officers can respond "professionally to the challenges of removing people with no right to be in the UK".
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They added: "This includes practical sessions so escorts have the skills they need to deal with different scenarios.
"As we ramp up removal activity we will continue to ensure new escorts have the training facilities necessary."
Speaking yesterday, after Rishi Sunak's Rwanda Bill passed its third reading, the Prime Minister said the Government is "intensifying" its preparations for the first flights to Kigali.