The Home Office has revealed it has only managed to contact three of around 60 people who may have been wrongly deported as part of the Windrush scandal.
Officials have searched through more than 8,000 records dating back to 2002 to find cases of Commonwealth citizens who may have been forced to leave for failing to provide the right documentation - despite living legally in the UK for decades.
The government has come under intense criticism over the treatment of the so-called Windrush generation of Caribbean immigrants, who moved to the UK between the 1940s and the 1970s but were never fully naturalised.
More than 5,000 people have been identified as potential Windrush cases since the scandal broke, when it emerged that scores of people who were entitled to be in the UK had lost their jobs, been denied medical care and threatened with deportation.
Newly appointed home secretary Sajid Javid admitted earlier this month that 63 people may have been wrongly deported or removed from the UK. Of those cases, 32 were classed as foreign national offenders, while 31 were people subject to "administrative" removals.
In a letter to Home Affairs Committee chair, Yvette Cooper, Mr Javid said the latter group are being "proactively contacted" through a specialist Windrush taskforce.
He added: "We have so far made contact with three and are asking high commissioners to assist where we do not have contact details.
"When we reach these individuals they will be invited to contact the taskforce."
The Home Office has also faced pressure to establish how many people have been detained as a result of the Windrush debacle.
Mr Javid said: "As with the removals exercise, this is a complex piece of work which involves manually examining thousands of cases in order to see whether there is anything on the record which suggests that someone could have been here before 1973 - likely to be a much smaller number.
"Officials believe that their initial investigations are likely to take between six and eight weeks."
The Home Secretary noted that there are people of the Windrush generation who, having worked all their lives in Britain, have retired to the country of their birth, disclosing that the taskforce has supported 11 individuals back to the UK and is handling 226 inquiries.
Responding to his letter, Ms Cooper said: "It remains a real concern that only three of the 63 potential wrongful deportations and removals have been contacted so far, and that it will take a further six weeks for the Home Office to assess how many people may have been wrongfully detained."
The Windrush scandal led to the resignation of Amber Rudd from Theresa May's top team and also overshadowed a recent Commonwealth summit in London, where the prime minister had to apologise to Caribbean leaders for the treatment of their citizens.
It also shone a light on Ms May’s time at the Home Office, where she introduced the hardline “hostile environment” policies blamed for the aggressive targeting of Windrush citizens.
Earlier, Mr Javid announced plans to waive fees for citizenship applications for children of the Windrush generation - who joined their parents before they turned 18 - and free confirmation of the existing British citizenship for children born to the Windrush generation in the UK.
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